* Closes Issue 34 [https://github.com/nvie/pip-tools/issues/34]
* Now pip-review log levels info and debug will be sent to stdout, and levels
  critical, error, and warning will be sent to stderr.
* Made same changes to pip-dump. However, pip-dump doesn't currently log any
  messages, so there will be no change in pip-dump's behavior.
Changing warning to info per nvie's request.
Fix formatting of .rst file.
Update HISTORY.
Merge branch 'master' into johnmarkschofield-master

Conflicts:
	bin/pip-review
Update HISTORY.