HUE-2312 [search] Create a new Leaflet map widget

Added Leaflet support on Search
HUE-2312 [search] Fixed some dashboard bugs
HUE-2312 [search] Added lat/lng field selector dropdowns
HUE-2312 [search] Map result set data to the leaflet marker
HUE-2312 [search] Show/hide map on dropdown change and toolbar restructure
HUE-2312 [search] Finalize marker map widget

Now points to real data.
Label is optional.
Automatically fetches needed fields.
Make sure to not fetch fields anymore if widget is deleted.
Adding a self.template.fieldsNames to get all the field names.
HUE-2300 [search] Adding support for discrete multibar chart for pivot
HUE-2300 [search] Linking real data to Pivot 2D chart
HUE-2312 [search] Fixed empty label on Leaflet map
[search] Improve detection of date type of facets

Fix stats query without a query object
Fix range selection of pivot facet
Fix loading leaflet with some missing labels
[core] Add warning and propose workaround for Ubuntu 14.04 build error