Add missing class

Reviewed at https://rbcommons.com/s/twitter/r/1414/
Allow rbtools to be used from anywhere

Testing Done:
I used this to post https://rbcommons.com/s/twitter/r/1412, because I didn't have another handy way to use rbtools.

Reviewed at https://rbcommons.com/s/twitter/r/1413/
Fix error in string formatting

1. Fix mis-spelled key "cateegory".
2. Simplify complicated format-within-format.

Testing Done:
Manual testing.

Reviewed at https://rbcommons.com/s/twitter/r/1416/
Exit workers on sigint rather than ignore

Testing Done:
https://travis-ci.org/pantsbuild/pants/builds/42139656

Also: ctrl-c'ed in the middle of cache fetch with and without this change.

Without: observe dots continue to print for several seconds after main process appears to exit. `killall python` required to stop them.
With: dots stop printing immediately, no python processes running.

Bugs closed: 829

Reviewed at https://rbcommons.com/s/twitter/r/1405/