Refactor of queries, filters, dashboard service

* Every panel support multi-query
* Customizable query colors and labels
* Queries, label and colors are synced across panels at all times
* New filtering functionality
* Filters can be toggled and removed 
* Drill down won't overwrite your queries, labels or colors
* Confusing group functionality has been removed
* Index configuration has been moved from the timepicker, to the main dashboard editor
* The stringquery panel has been replaced with a more polished 'query' panel