Adds the ClientCertificate to the Request

For Hosting.Aspnet, Hosting.Wcf and Hosting.Owin. I've also done a
pull-req to https://github.com/prabirshrestha/simple-owin/ to make that
send the Certificate on in the ssl.ClientCertificate env variable.
In tests the ClientCertificate property is null.

IIS fills this with an empty object. Thats why I check for .Length == 0.
Code clean up. And added the certificate to the

OWIN env in the owin demo. So I can refer to that in the documentation.
Bit more Stylecop OCD.
Also adds the ClientCertificate in Hosting.Self
Correctly set URL and path for requests to WCF services whose base URIs do not have trailing slashes
Fixed incorrect spacing convention
Changes according to @thecodejunkie

WCF Claimset doesn't assume [0] is the X509CertificateClaimset anymore.
And the certifcate variable name is now the same in every host.
Forcing MSBuild to use v10.0
Merge pull request #1040 from thecodejunkie/modifiedmsbuildrake

Forcing MSBuild to use v10.0
Used string.Concat instead of operator to concatenate strings
Added Given/When/Then comments to WCF fixture
Merge pull request #1038 from bwatts/WcfTrailingSlashFix

Correctly set URL and path for requests to WCF services whose base URIs do not have trailing slashes
Updated xunit to latest stable
Merge pull request #1043 from thecodejunkie/xunitupdate

Updated xunit to latest stable
Fixed broken xunit reference
Fix typo
Merge pull request #1045 from jugglingnutcase/patch-1

Fix typo in Browser.cs
Fix issue with login request helper

Any POST to the diagnostics app was being treated as a login request.
Merge pull request #1048 from jugglingnutcase/diagnostics-login-fixes

Fix issue with login request helper. Fixes #1047