preparations for Ember.js transition
JSON API (/v2/api.php) added

API calls look like this: /v2/api.php?namespace.function(arg1,arg2,...)
Example call (fetches all Sensor 1 data for the last two quarters in 2013): /v2/api.php?device.read(s1,2013-07,6m)
API functions for account editing, authentication, data fetching, backup & language settings
minor bug fixes