Remove Exports Reliance

Won't work from a command prompt.
Support Testing on Windows
- Skip the iOS tests (they rely on Mac tools like xcode to run)
- Make the Android SDK existence testing a bit more flexible and clear when it fails.
- If env.TMPDIR doesn't exist, fallback to env.TEMP. Also override env.TMPDIR via lib/test.js, because instanbul doesn't handle this fallback internally (AFAIK).
Merge pull request #138 from dawsontoth/npmTestOnWindows

Get Tests Running on Windows