adapt link 0.4 API, shared selector between clients
use agent for background computing
unchecked-inc for transaction id generator
Merge branch 'master' into 0.9-dev

Conflicts:
	project.clj
Update README.md
Merge branch '0.9-dev'
bump version 0.9.0
Merge remote-tracking branch 'upstream/master'

Conflicts:
	project.clj
	src/slacker/client/common.clj