Add ActionWatcher on state
Add ok check for interface{} --> string type assertion
Add tests for coalescing added actions, and excluding removed actions
Merge pull request #128 from johnweldon/action-watcher

Add ActionWatcher on state

First part of adding Action Watchers. Start with state package and will move on to api and apiserver packages next.
Added file size limit of 5M.
Merge branch 'master' of https://github.com/juju/juju into set-add-at-syntax