Added Date and Time Picker

This commit includes two new types for option-tree. Date Picker only
calendar and Date Time Picker with Calendar and Time. Both types were
tested with wp3.8 in twentyfourteen.
Indentation Fix
Merge branch 'wip' of github.com:jetonr/option-tree into jetonr-wip
clean up
rename time picker
separate option descriptions
date & time picker styles
date & time picker styles