Add property to set a custom UITextField class to use

Helps with customization of appearance (text in the text field can be properly aligned using a subclass)
Fix static analysis warning

Setting an NSMutableArray pointer with an NSArray
Support "Enter" key on keyboard

Move to next text field or trigger the last "otherButtons" action when "Enter" key is pressed on the keyboard
Align alert view on pixel instead of sub pixel so it's not blurry on non-retina screens
Merge pull request #16 from mirego/custom-uitextfield-class

Add property to set a custom UITextField class to use
Merge pull request #17 from mirego/fix-static-analysis-warning

Fix static analysis warning
Merge pull request #18 from mirego/support-enter-key

Support "Enter" key on keyboard
Merge pull request #19 from mirego/non-retina-blurry-fix

Align alert view on pixel instead of sub pixel so it's not blurry on non-retina screens
Merge remote-tracking branch 'upstream/master' into develop

Conflicts:
	AHAlertView/AHAlertView.m