Add methods that can pin multiples edges

Add methods that can pin multiples edges:

• all(): Pin all edges on its superview's corresponding edges (top, bottom, left, right). Similar to calling view.top().bottom().left().right()

• horizontally(): Pin the left and right edges on its superview's corresponding edges. Similar to calling view.left().right().

• vertically(): Pin the top and bottom edges on its superview's corresponding edges. Similar to calling view.top().bottom().

Added by Luc Dion in Pull Request #93

View build details and download artifacts on buddybuild:
PinLayout (iOS, PinLayout)