Adding infrastructure for building ui components
Added working, but ugly zoom slider
Added some data for icons
Styled zoom slider
Implemented clicking on the track of the zoom slider
Added docstrings for the slider widget code
Added a basic test of the zoom slider
Remove slider background
Making the controls a bit bigger
Easing on zoom in/out
Added a transition effect for clicking on the track
Added a contrast transition in slider
Resetting map center on zoom
Moved ui to geo.gui
Merge remote-tracking branch 'origin/ui-controls'

Conflicts:
	src/core/map.js
Merge pull request #238 from OpenGeoscience/resolved-merge-ui

Resolved merge ui