Create the GrammarStatusView. Pull out of status bar

[benogle]

Use the status-bar api to add the selector link to the status bar. This seems to be the first time one package is reliant on another package. Couple things:

I dont like the method of waiting for the status bar.

The grammar selector could be activated before the status bar. So I have this:

createStatusEntry = ->
  view = new GrammarStatusView(atom.rootView.statusBar)
  atom.rootView.statusBar.appendLeft(view)

if atom.rootView.statusBar
  createStatusEntry()
else
  atom.packages.once 'activated', ->
    createStatusEntry()

Would be nice to put something in the package manager or the root view to make this easier. The status-bar can put it in the rootView? Not sure what that looks like yet.

Testing the addition to the status bar

I cant load the status-bar package from the specs (though it will load the language grammars, so maybe something else is going on??). So I am mocking the status bar. Not a huge amount of code, but it would be nice to use the real one in case of api or behavior changes. How do you guys feel about using the real package vs using a mock??