Invalidate intrinsic content size when attributed text changes

Signed-off-by: Mattt Thompson <m@mattt.me>
Adding social_media_url to podspec
Added Core Text kern attribute

Set it to 0.0 to avoid kerning so that it renders the same as UILabel
and UITextView.

Conflicts:
	TTTAttributedLabel/TTTAttributedLabel.m
[Issue #311] Adding call to CATransaction flush to make link tapping more responsive

Adding QuartzCore imports and dependency to podfile

Signed-off-by: Mattt Thompson <m@mattt.me>
Adjusting default offset of highlight outline