Remove telerik

[bkindig]

No description provided.

[bdukes]

We still need to:

• Remove line from ReadMe about Telerik license requirement
• Update packaging, since we aren't generating separate packages for DNN 5.1 vs. 5.2+
• Fix obsolete code warnings from upgrade to DNN 6.0

[bdukes]

Let's also switch to pulling in the DNN & Telerik references from NuGet, so referencing http://www.nuget.org/packages/DotNetNuke.Web/6.0.0 and http://www.nuget.org/packages/DotNetNuke.Core/6.0.0, and making sure not to check in the packages folder (I may need to update the build definitions on TeamCity to pull in NuGet, so don't freak out too much if GitHub complains that the build for the pull request failed)