bump to 0.12.0

Merge branch 'agent-preserve-closed-channel' of https://github.com/tbetbetbe/agent into tbetbetbe-agent-preserve-closed-channel

use 2.3.1 for travis

update deps

update .travis.yml to use latest ruby versions

Merge pull request #26 from tbetbetbe/agent-fix-travis-change-jruby-timeout

Merge pull request #27 from tbetbetbe/agent-speedup-travis

Updates .travis.yml to improve build speed

Updates a test timeout that is too small on jruby

Allows receivers of closed channels to receive the contents of the channel.

Bumping version to 0.11.0

Add specs proving that closing channels triggers select

Merge pull request #23 from tbetbetbe/fixes_behaviour_of_select_for_closed_channels

Removes an unnecessary return

Corrects the behaviour of select for closed channels