Usability Improvement and Fatal Error Fix

* All: Updated README.md. Added the steps that Visual Studio 2013 should be run as Administrator.
* NuGet: In Add-PrigAssembly command, added the feature to enable that the full path to stubbing assembly is specified. This will allow that you can add Prig Assembly that is not registered to GAC.
* NuGet: Added support for generating constraints of generic parameters automatically.
* NuGet: Fixed #1: BadImageFormatException occurred. => As expected, it did not consider the configuration Any CPU + Prefer32Bit.
* NuGet: Added the feature to make the constructor indirection target.
* NuGet: Improve debuggability.
* Framework: Fixed #2: Shall the name attribute be unique in the Stub Setting? => No, it shall not. This is a simply wrong implementation.
* prig: Enhance the feature 'dasm'. Added support to get the information of the assembly that is not registered to GAC, and to be able to get more meta data.