Add support for the Wire protobuf library.  Adds the java_wire_library() target.

https://github.com/square/wire

Testing Done:
Added an example, plus new unit and integration tests.
CI is running @ https://travis-ci.org/pantsbuild/pants/jobs/39988400

Bugs closed: 765

Reviewed at https://rbcommons.com/s/twitter/r/1275/
Remove some remaining old options references.

Testing Done:
CI passed. Manual testing of cmd-line flags.

Reviewed at https://rbcommons.com/s/twitter/r/1317/
docs: confluence-publish's wiki info lives in a plugin now.

also, give a sample ConfluencePublish goal.

Bugs closed: 723

Reviewed at https://rbcommons.com/s/twitter/r/1299/
doc: update import path for PEX

"I don't see any code still importing twitter.common.python pex (except for examples in rst files,which should probably be fixed)"

Bugs closed: 428

Reviewed at https://rbcommons.com/s/twitter/r/1298/
switch src/* usages of Config.load to use Config.from_cache instead

Now all usages of Config.load in src use a cache if the config already has been parsed.

This doesn't change test usages, but since tests use temp directories, tests with different ini files don't interfer

Testing Done:
ran ci.sh locally

travis ci in progress: https://travis-ci.org/pantsbuild/pants/builds/40687043

Bugs closed: 788

Reviewed at https://rbcommons.com/s/twitter/r/1319/