rosie: add gpg-agent caching of credentials.

This uses the gpg-agent Assuan protocol to communicate via
a socket. It uses gpg-agent's own password entry mechanism
(the pinentry programs).
properly escape prompt spaces
alter cache id and prompt string
Fix rose command PYTHONPATH test

It was failing if `lib/bash/rose_init_site` added any site specific
items into PYTHONPATH.
rosie auth: clear gpg cache for bad passwords
Merge pull request #1470 from matthewrmshin/fix-pythonpath-test

Fix rose command PYTHONPATH test
Merge pull request #1464 from benfitzpatrick/rosie.gpg-agent

rosie: add gpg-agent caching of credentials.
rosie.svn_post_commit: more notification

(Or at least that's what this change will become.)