Added basic Maya 2014 debug and release configurations to Xcode project.
Fixed unordered map include path for OS X.
Fixed unordered map dependent type definition on OS X.
Updated MAYA_PATH for 2014 configurations in Xcode project.
Moved Xcode project to libc++.
Removed reference to nonexistent header file on OS X / Clang.
Added definition for missing operator<< with libc++ (std::__1) ostream& and const MString& under OS X.