change --save-dev to --save for bower install

**Not an issue!! Just a Suggestion...**

in REAME file change `bower install angularjs-color-picker --save-dev` to `bower install angularjs-color-picker --save`. 

--save-dev includes dependency as dev-dependency in bower.json which causes problem in automating flow with wiredep like tools. 

Thanks,
Cheers and great work !!!
