Test touchView class instead of assert

It might happen that other views are added as subviews of the key window, e.g. https://github.com/defagos/CoconutKit/blob/2.0.2/CoconutKit/Sources/Animation/HLSLayerAnimationStep.m#L90
So it is better to just test rather than assert in order not to crash.
Merge pull request #6 from 0xced/no-assert

avoid assert so as to not crash (credit: @0xced)
Added trailing newline to source files to conform to local conventions/warnings.
Force a build error (via #error) if DSFingerTipWindow.m is built without ARC
enabled.
Merge pull request #7 from correia/master

Add trailing newline to source files; fail to build if ARC is not enabled
transition to MapBox
better README
update podspec
revert accidental debug commit
capitalize