Fixes gh-178

This small change now plays nice with wildcard classpath
entries coming from a parent classloader as its urls.

Long package names are really unnecessary in samples and they
just clutter things up. Also Spring Loaded doesn't work with
org.sfw packages, so to demo that technology you need a
different package name.

Main user-facing interface is still Counter/GaugeService but the
back end behind that has more options. The Default*Services write
metrics to a MetricWriter and there are some variants of that, and
also variants of MetricReader (basic read-only actions).

MetricRepository is now a combination of MetricReader, MetricWriter
and some more methods that make it a bit more repository like.

There is also a MultiMetricReader and a MultiMetricRepository for
the common case where metrics are stored in related (often open
ended) groups. Examples would be complex metrics like histograms
and "rich" metrics with averages and statistics attached (which
are both closed) and "field counters" which count the occurrences
of values of a particular named field or slot in an incoming message
(e.g. counting Twitter hastags, open ended).

In memory and redis implementations are provided for the repositories.
Generally speaking the in memory repository should be used as a
local buffer and then scheduled "exports" can be executed to copy
metric values accross to a remote repository for aggregation.
There is an Exporter interface to support this and a few implementations
dealing with different strategies for storing the results (singly or
grouped).

Codahale metrics are also supported through the MetricWriter interface.
Currently implemented through a naming convention (since Codahale has
a fixed object model this makes sense): metrics beginning with "histogram"
are Histograms, "timer" for Timers, "meter" for Meters etc.

Support for message driven metric consumption and production are provided
through a MetricWriterMessageHandler and a MessageChannelMetricWriter.

No support yet for pagination in the repositories, or for HATEOAS style
HTTP endpoints.

Added the necessary @ConditionalOnMissingBean annotations to allow selectively declaring an EntityManagerFactoryBean, a JpaVendorAdapter or a PlatformTransactionManager. Especially the first one might be necessary to make sure the persistence provider evaluates an orm.xml. This unfortunately rules out using the packages to scan feature of Spring's LCEMFB.

I've filed https://jira.springsource.org/browse/SPR-11260 to potentially remove the need for this workaround in Spring itself.

Change configuration to use ConfigurationProperties instead of direct access to environment for MBean export

Rework EndpointMBeanExporter to prevent name clashes and to provide more flexibility in naming of endpoint MBeans

If Logback and another SLF4J implementation are both on the classpath
it is possible for the LogbackLoggingSystem to fail to locate
a LoggerContext. Rather than a ClassCastException it is better to
make an assertion with an error message.

Fixes gh-162

Fixes gh-147

    $ ant -lib ivy-2.2.jar

(substitute the location of your actual ivy jar)

    $ java -jar target/*.jar

Fixes gh-140

Fixes gh-181

User can now do this, for instance:

    @Configuration
    @PropertySource("classpath:my.properties")
    public class MainConfiguration {}

    @Configuration
    @PropertySource("classpath:foo.properties")
    @Profile("foo")
    public class FooConfiguration {}

and the "foo" properties ar eonly loaded in the "foo" profile.

If any of the sources has a @PropertySource annotation (or many)
then we can add those properties to the Environment. It's a nice
convenient way of specifying a custom external properties location
for an app.

One problem is that Spring will come along and parse the same
annotations later as part of the @Configuration parsing. The
user has pretty limited control over how that is done, and it
will never be done in a "natural" way for a Boot application
(which would prefer that the default application.properties
is applied *last*, whereas Spring will apply the @PropertySource
last).

To get round that problem we add the property sources with
a different name (key in the PropertySources in Environment),
prefixing named property sources with "boot.", and adding
others with a name that is the same as the resource location
(instead of its description, which is the default for
Spring).

Another problem is that Spring doesn't know about YAML, so
the user is currently restricted to using properties files
with this annotation.