Passphrase: expand triggers.

Will now respond to queries like "5 word passphrase", "pass phrase 3
random words" and even "create random passphrase"

Tests updated to be more robust, cover the example queries and show
some new possibilities.

Also adds an abstract to reduce the scroll-spam on `dzil test`

Big thanks to @moollaza for both the suggestion and guidance.
Merge branch 'master' into flexible_passphrase
Merge pull request #320 from mwmiller/flexible_passphrase

Passphrase: expand triggers.