Will not build with android NDK

[toonetown]

The android NDK does not have std::stoi or std::to_string defined (see http://stackoverflow.com/questions/17950814/how-to-use-stdstoul-and-stdstoull-in-android/18124627#18124627 for some discussion about it).

These functions are used by the uri library to handle port conversion.

I am willing to look into fixing the issue and submitting a pull request, but am wondering what the best approach would be? Just defining these function within an #ifdef __ANDROID__? Using something like boost::lexical_cast? Creating new functions? Other suggestion that I may have missed?

[toonetown]

A pull request has been submitted as #57 - I would suggest tracking the discussion of this issue there.