Add colorpicker field type

Add a colorpicker field type to the list of available fields. Makes use
of the internal wpcolorpicker plugin so matches the customizer nicely.
Small tweaks

Fix tab indentation
add quotes around attribute
revert

revert some changes that I was testing and shouldn’t have made :)
space to tab
Merge pull request #108 from BinaryMoon/master

Add colorpicker field type