Log OCUnit run failures to stderr for AppCode / Support matching UIGeometry structs

Moving test output over to stderr improves AppCode integration, in that failures now appear in the test tree navigation pane. More work is needed here but it's a start.  Also, we gave the sample app a rootViewController to squelch a warning when running Cedar's own OCUnit integration specs.

Finally, there is a commit here which adds basic UIGeometry struct matching to the Cedar-iOS static framework.  These matchers are only imported when building for iOS.  Hopefully the technique used in ComparatorsBase.h is the desired way to govern this.