Updating Control.addStyles()

To accept object as parameter in addition to string css
Optimize new addStyles implementation

Going from object to string to parsed-string wasn't needed,
so we can instead just directly assign into domStyles then run
changed handler.  Tested from web console.

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Merge pull request #632 from enyojs/LEX-STYLES

Updating Control.addStyles()

Reviewed-By: Ben Combee (ben.combee@lge.com)