Upgrade to com.twitter.common#jar-tool;0.1.6

This picks up a fix for moving the temporary jar file created
to it final target location when the two reside on different
filesystems.

Testing Done:
$ PANTS_DEV=1 ./pants goal binary bundle src/java/com/pants/::

Bugs closed: 193

Reviewed at https://rbcommons.com/s/twitter/r/465/
Updated build file parser error message when the same target is redefined

Testing Done:
Added a new test in test_build_file_parser.py and updated an existing one.

I tested with

PANTS_DEV=1 ./pants tests/python/pants_test/base:build_file_parser --verbose

but am currently unable to retest or run ci because of the ... untranslatable ... errors.

Bugs closed: 192

Reviewed at https://rbcommons.com/s/twitter/r/464/
Protobuffers can read in .zips, .jars, .tars, .tar.gzs, and .tar.bz2s containing proto files (or directories of protofiles, etc) as sources.

This is done fairly generically to minimize how much protobuf_gen knows or cares about the exact format of the input files, with the goal of making it easy to extend this functionality to other targets (and other kinds of compressed files). The ultimate goal is being able to read zip files from remote repositories.