Redesigned the resolution mechanism for injecting platform-specific services in the PCL core assembly with code borrowed from http://pclcontrib.codeplex.com/
The build script wasn't updating all solutioninfo.cs files.
Merge pull request #132 from dennisdoomen/119_PclDetection

Redesigned the resolution mechanism for injecting platform-specific ices services in the PCL core assembly with code borrowed from http://pclcontrib.codeplex.com/.

Should fix #126 and #119.