Added mergeHaltL,R,Both, fixed termination behaviour of Exchange.run
Merge branch 'master' of github.com:scalaz/scalaz-stream into exchange/run.fix

Conflicts:
	src/main/scala/scalaz/stream/Process.scala
Tests for resource safety of pipe
Merge pull request #145 from scalaz/exchange/run.fix

Exchange/run.fix
Merge pull request #148 from radekm/resource-safety-pipe-tests

Tests for resource safety of pipe