Reapply "Remove unused methods from GitHttpServerRegistrationHandler."

This reverts commit e1d9baf805a284487904a2e0dcdafca53f579065.

Conflicts:
	fabric/fabric-git-server/src/main/java/org/fusesource/fabric/git/http/GitHttpServerRegistrationHandler.java
Reapply "Simplify Git services. Clean cashes on external pushes."

This reverts commit 2c2524df02ad3af7c4eb917a11b1d4d565966869.

Conflicts:
	fabric/fabric-git-hawtio/src/test/java/org/fusesource/fabric/git/internal/GitDataStoreTest.java
	fabric/fabric-git-server/src/main/java/org/fusesource/fabric/git/http/GitHttpServerRegistrationHandler.java
	fabric/fabric-git-zkbridge/src/main/java/org/fusesource/fabric/git/zkbridge/Bridge.java
	fabric/fabric-git/src/main/java/org/fusesource/fabric/git/internal/CachingGitDataStore.java
	fabric/fabric-git/src/main/java/org/fusesource/fabric/git/internal/FabricGitServiceImpl.java
	fabric/fabric-git/src/main/java/org/fusesource/fabric/git/internal/GitDataStore.java
	fabric/fabric-git/src/main/java/org/fusesource/fabric/git/internal/LocalGitService.java