Read arguments for thrift-linter from pants.ini.

This allows changing linter options without changing pants.

Testing Done:
./build-support/bin/ci.sh

PANTS_DEV=1 ./pants goal thrift-linter testprojects/src/thrift/com/pants/testproject:thrift-java

Bugs closed: 719

Reviewed at https://rbcommons.com/s/twitter/r/1215/
Add support for updating the environment from prep_commands.

Reviewed at https://rbcommons.com/s/twitter/r/1222/