various container implementations which  resolves #2

Removed the direct dependency on StructureMap.
Allow setting DependencyResolver using Funcs.
Added IDependencyResolver implementations for Autofac, Ninject, Unity, Windsor and of course StructureMap.
Nuspec files for the new container implementations
Merge pull request #12 from kmc059000/various-container-support

various container implementations which resolves #2