#36 Error when installing NuGet package

The tl;dr version:
Sorted Femah.Core.nuspec file to allow consumption of Femah.Core nuget
package by third party applications.

The full version:
- Modified Femah.Core.nuspec to only copy Femah.Core.dll (odd as I still
don't know where mscorlib.dll was being copied from
- Modified Femah.Core.nuspec to correctly have a dependency on
Newtonsoft.Json (rather than packaging it in the lib folder), also
dropped it down to a minimum of v4.5.11 from a previous minimum of
v5.0.6.  This was mostly due to WebAPI and WebGrease puking in my face
and getting all precious about versions of Newtonsoft.Json (a lot of the
box MVC template solution relies on Newtonsoft.Json) when Femah.Core was
installed in a fresh MVC5 .NET45 web app.  I figure it's best to have
the minimum version dependency possible.  Saying that, we should work
out how we're going to test Newtonsoft.Json if we're not going to tie it
to a particular version.
- Modified Femah.Core.nuspec to correctly copy Femah.Core.dll to a
\lib\NET45 folder (instead of NET4) as we're currently building it in
.NET 4.5, we need to address this and support a far lower framework
version.
- Updated git to stop tracking TestResult.xml
- Continued to keep all femah\packages within source (maybe we should
use true NuGet package restore, maybe we shouldn't), personally I don't
want to for femah at the moment, maybe a different story for
femah.examples though.
Merge pull request #37 from lholman/master

#36 Error when installing NuGet package