Initial rubocop support.

Per the mailing list thread, introducing Rubocop as a replacement for Tailor.
Assuming Jenkins likes this, more pedantic patches will follow to make Rubocop
happy.

rubocop              | 24 files inspected, 1617 offences detected

Change-Id: I10077146fbaa015c4b74cac826761de273c5639d
Merge "Initial rubocop support."