Closes #1160

Closes #1159

Closes #1158

Closes #1157

Closes #1156

Closes #1155

Closes #1154

Closes #1153

Closes #1152

Closes #1151

Closes #1150

Update ExecutableArchiveLauncher so that `-cp` URLs are not added
when they are already contained as nested JARs. This prevents a
SecurityException "signer information does not match error" when using
signed jars. The root cause of the issue was that the primary JAR file
was on the default classpath with the URL "file:....jar" and in the
main URL set as "jar:file:....jar". It is now filtered so that only
the "jar:" variant is added.

Fixes gh-1134

* The SpringApplicationBuilder was registering the parent context initializer
twice (not really a problem, but confusing if you are debugging).

* ParentContextApplicationContextInitializer itself should have been
checking that the current context is not the parent

* The EventPublishingRunListener as a result needs to call
setApplicationContext on any listeners that are AplicationContextAware

* ParentContextCloserApplicationListener can ensure that there is
only one of its kind per application context by implementing hashCode
and equals

Fixes gh-1142

Fixes gh-1141

Update the executable JAR code to automatically unpack any entries
which include an entry comment starting `UNPACK:` to the temp folder.
The existing Maven and Gradle plugins have been updated with new
configuration options and the `spring-boot-tools` project has been
updated to write the appropriate entry comment based on a flag passed
in via the `Library` class.

This support has been added to allow libraries such a JRuby (which
assumes that `jruby-complete.jar` is always accessible as file) to work
with Spring Boot executable jars.

Fixes gh-1070

Add a Library class update the LibraryCallback interface and
implementations to use it. This change is in preparation for
an addition `unpack` flag that will be required to allow the
automatic unpacking of certain nested jars.

See gh-1070

Update JarURLConnection to allow the resolution of items within a nested
jar, even if the jarFile passed to the connection is several levels up.

This prevent a connection from incorrectly resolving an entry against
the wrong jar file.

See gh-1070

Drop `RepackageTask.getDependencies` from the gradle plugin in favor of
exposing `getLibraries()` and using the callback.
Drop getDependencies

Extract the nasty Tomcat resource handling reflection code to its own
class.

Stretches the Gradle boot plugin a bit, so there's a sample build
in the "profile" sample. Howto docs give examples.

Fixes gh-1135

Fixes gh-1133

bean from the registration of Jackson modules to avoid circular creation
of the default ObjectMapper bean (and thus failing to obtain the ObjectMapper
and registering the module(s)).

Fixes gh-1132

See gh-1113

Tomcat 8 has different APIs again so it was quite difficult to
get it working and test it. The test is manual anyway (multi-module
project with JSPs in /META-INF/resources, not part of the samples),
and requires you to build a war and execute it (since the resource
paths are different when it's an archive).

Fixes gh-1131

Fixes gh-1130

See gh-1113