In the server we use a SpringApplicationEnvironmentRepository to load
the YAML and properties files from git (or locally). It creates a mini
SpringApplication so as to faithfully replicate the way the Environment
is created. Unfortunately that can have side effects on the server
application itself (e.g. setting log levels). In particular if the
mini SpringApplication fails to start then the log levels could be
left in a "preInitialized" state with all log levels OFF by default.
This change ensures that the server logs all errors when loading YAML
and properties files, and also that the client logs the error response
if it is JSON (as it should be).
Fixes gh-66, fixes gh-67
ConfigServerProperties is now used to store global properties
for the config server (like the path prefix and bootstrap flag)
under spring.cloud.config.server.* so git specific ones have
been pushed down to spring.cloud.config.server.git.* (similarly
for git->native).
At the same time introduce spring.cloud.config.server.defaultLabel
for the deafult git label (defaults to "master").
Fixes gh-28
