feat(library): ItemView Public Method Additions

Added the following category: UILabel+frameFitting - See addition 3 below

1) setBackgroundImage:forState:withInsets:
- purpose: For precise image placement and sizing
- params: UIImage of icon, ADDropDownMenuITemViewState, and a UIEdgeInstes for where to place the icon
- This allows us to set icon images the proper way with out have to recreate an icon to have white space
- setBackgroundImage:forState: body has been refactored into this method
- setBackgroundImage:forState: uses this method as a base method passing it UIEdgeInsetsZero

2) setTitleText:forFont:
- purpose: For precise control over the font and title setting at the same time
- Sure we could have just directly access the label but it usually pretty common that devs would want to set the font too
- So why not both at once?

3) setTitleOffset:
- purpose: For precise vertical placement of the title label
- params: UIOffset for offsetting the label based off the top of the item view
- This method utilizes a category added `UILabel+frameFitting` that fits the frame of the label to the size of the text