Issue:7393 [MT] Update deployment target to iOS 7

Replace sizeWithFont:constrainedToSize: with threadSafeSizeWithFont:constrainedToSize: which uses boundingRectWithSize:
Round up threadSafeSizeWithFont: values to correctly match deprecated sizeWithFont: behaviour
Update deployment target to iOS 7

Replace sizeWithFont:minFontSize:actualFontSize:forWidth:lineBreakMode: with safeFractionalSizeWithFont:minFontSize:actualFontSize:forWidth:lineBreakMode: