Changed iterator used during import, so it can replace fid and feature type

That functionality had been mistakenly left aside after changes made to improve performance
added --tree-stats option to diff-tree
added export-diff op and shp wrapper
Merge remote-tracking branch 'origin/pr/538'
Made iterator throw exception if value to use for fid is null. Before, it used the default geotools-assigned fid
Merge branch 'mongo-cli' for configuration changes

Conflicts:
	src/cli/pom.xml
	src/cli/src/main/java/org/geogit/cli/CLIInjectorBuilder.java
Merge remote-tracking branch 'origin/pr/539'
Avoid flaky git commit plugin in Travis builds
Merge remote-tracking branch 'origin/master' into plugins

Conflicts:
	src/cli/pom.xml
	src/cli/src/main/java/org/geogit/cli/CLIInjectorBuilder.java