Add setting in modal
Save channels in Connection.onClose

- Make all settings uppercase and snake_case
Listen to onunload and onbeforeunload for channel saving

- Fix bug where $scope.connected will be reset to false when the user joins a channel
Join preserved channels if the setting is enabled
Fix bug where user could not remove channels from the autojoin list

When a user recieved a PART message, it was only processed
for other users and not for himself, so the channel was never
removed from his list.
Migrate previous settings to new keys
Ensure that the old setting exists before deleting it
Check that the CHANNELS array isn't empty
Merge pull request #45 from coldstorm/setting/preserve-channels

Preserve channels when disconnecting