Add LuaJIT support on iOS and OS X

*  LuaJIT build process is automated
    * The new shell scripts are added to the libmoai-ios and libmoai-osx targets as a script build phase
*  LuaJIT can be disabled by following the instructions in the README
   * Remove linking of LuaJIT
   * Set the MOAI_WITH_LUAJIT variable to 0 
   * Link against the newly created targets libmoai-osx-lua and libmoai-ios-lua

I'm aware of other efforts such as issue #662 which was closed by Patrick stating that they wanted to wait for cmake build system.  

Currently Cmake is broken for OSX so I feel this PR will at least allow users of Moai to make use of the performance that LuaJIT offers until this problem is resolved.