Removed pants() references in all project BUILD files

Followon to https://rbcommons.com/s/twitter/r/903/

Mechanical refactor of BUILD files to get rid of deprecated use of pants() wrapper around targets:

    sed -i "" -e 's/pants(([^)]))/\1/g' `find . -name "BUILD"`

Testing Done:
CI is green (https://travis-ci.org/pantsbuild/pants/builds/32717695)

Bugs closed: 487

Reviewed at https://rbcommons.com/s/twitter/r/904/