twitter agents can be disabled too
Merge branch 'master' into twitter_is_optional_too

Conflicts:
	Gemfile
Merge pull request #536 from cantino/twitter_is_optional_too

twitter agents can be disabled too
Update ffi to 1.9.5.  Seems 1.9.4 has been yanked.
avoid quotes in .env example
Add two specs for Agent#destroy to cover redirects
Merge pull request #553 from amoeba/add_specs_for_agent_destroy

Add two specs for Agent#destroy to cover redirects