modified grunt css task to copy only the changed file CDB-2807
CDB-2807 #resolve - grunt development processes improved
CDB-2810 #resolve - added nasa basemaps
CDB-2810 - added error + fixed date problem
changed attribution + added date in NASA name + other fixed
hiding date combo when night type is selected in NASA tab
fixed and added tests for basemap chooser
Merge pull request #401 from CartoDB/CDB-2810

CDB-2810
changed text in nasa pane when date is not valid
CartoDB frontend assets version changed
Merge pull request #402 from CartoDB/CDB-2814

Changed text in NASA pane when date is not valid + frontend assets version changed
Merge branch 'master' into CDB-2811

* master:
  CartoDB frontend assets version changed
  changed text in nasa pane when date is not valid
  fixed and added tests for basemap chooser
  hiding date combo when night type is selected in NASA tab
  changed attribution + added date in NASA name + other fixed
  CDB-2810 - added error + fixed date problem
  CDB-2810 #resolve - added nasa basemaps
  CDB-2807 #resolve - grunt development processes improved
  modified grunt css task to copy only the changed file CDB-2807