Merge remote-tracking branch 'commons/master'

Conflict resolution notes:

build-support/python/setup.sh
  They added python 2.7 support, obviating the need for our patch.

pants.ini
  -> We have an added comment, and moved some python build cache
locations to homedir.

src/python/twitter/pants/python/thrift_builder.py
  -> We added 'utf8strings' to python thrift gen options.

src/python/twitter/pants/tasks/binary_utils
  -> We had added a print statement.  Discarded as upstream removed this
file.

src/python/twitter/pants/tasks/idea_gen
  -> We had wrapped a method call with 'list'.  Upstream made substatial
changes so hopefully obviated the need for this. (Edit, turns out this
wrapping is still needed.)

All other files to the best as I could tell had no necessary local
changes, so we just used
upstream.

Conflicts:
	build-support/python/setup.sh
	pants.ini
	src/python/twitter/common/python/installer.py
	src/python/twitter/common/python/resolver.py
	src/python/twitter/pants/python/thrift_builder.py
	src/python/twitter/pants/tasks/binary_utils.py
	src/python/twitter/pants/tasks/idea_gen.py
	src/python/twitter/pants/tasks/javadoc_gen.py