Fixed ARC warnings

Xcode 4.3 complains that "Default property attribute 'assign' not
appropriate for non-gc object"
Merge pull request #19 from stevewilford/master

Fix default property attribute warning on internalTextView
Added animationDuration property
Added animationDuration to the README
adding a new method that forces a resize of the textView's height (in cases where you've changed max/min lines)
add podspec
rename so cocoapods recognizes the podspec correctly
close brace in podspec
Merge pull request #28 from twistle/master

minor addition to allow programmatic access to force a re-size
Merge pull request #24 from mattrubin/animation-duration

Added animationDuration property