Fix bug in build-with-buck with library targets

Created by: adamhowardprice

Summary: Running buck project //src:foo --build-with-buck creates a project that cannot be built in Xcode if //src:foo is a library target. Previously we used one shell script that 1) built the project with Buck and 2) fixed UUIDs in the binary. Now we add the shell script to build in all cases, but only add the fix_uuid script if it is an apple_bundle.

Test plan: Unit tests updated. ant java-test -Dtest.class=ProjectGeneratorTest. Also, build an apple_bundle, apple_binary and apple_library, with buck project <target> --build-with-buck --combined-project and make sure all generated Xcode projects build correctly.