Stop tracking app/scripts-src/messageview.js

Somehow this missed the de-tracking of generated files earlier.
Rename SubscriptionPanel to SettingsPanel.

It's going to contain more than just subscriptions.
Rename 'settings' to 'uiState'.

A lot of places use 'settings' to refer to the current state of the
UI. This will be confusing when we have actual settings.
Show the existing zsig in the settings panel.
Persist zsigs on the server.

This uses a "zsigs" property so as to not collide with the current
"zsig" one.
Pick a random zsig when the message is sent.
Minor settings panel fixup.
Mark zsig remove buttons by index.
Use an <input> for zsig entry.
Hide overly-long zsigs.
Fix settings panel zsig widths.
Move settings panel close button to upper right.
Rename _subscriptions.scss to _settings.scss.
Merge branch 'zsigs' into roost-2-init

Conflicts:
	app/coffee/model/RoostSession.coffee
	app/coffee/view/ComposeBar.coffee
	app/coffee/view/FilterBar.coffee
	app/coffee/view/MessagePane.coffee
	app/coffee/view/MessagePaneView.coffee
	app/coffee/view/MessageView.coffee
	app/coffee/view/NavBar.coffee
	app/coffee/view/SettingsPanel.coffee
	app/sass/main.scss
	app/templates/SubscriptionPanel.hbs
Merge branch 'roost-2-init' of https://github.com/roost-im/roost-client into roost-2-init