WebMP: Add support for token-based downloads (closes #369)

This allows download links to be used from a different PC or browser, or to
send them to a third party, which can then download only the specified item.
The tokens are valid until the server is restarted.
Solution: Enable NuGet automatic package restore
WebMP: Update jQuery (UI) and remove unused JavaScript libraries
WebMP: Update project to ASP.NET MVC4
WebMP installer: Also ship ASP.NET MVC4 with the IIS installer
WebMP: Also get MoreLinq with NuGet
Configurator: Get Hardcodet.Wpf.TaskbarNotification and zxing libraries from NuGet
Libraries: Download System.Data.SQLite and JSON.NET with NuGet too
Solution: Add NuGet.config file to solution
WSS: Get MediaInfo library with NuGet
WSS: Get ffmpeg from NuGet and update to v1.2
Solution: Fix default platform in a lot of projects

Apparantly the default platform was still set to AnyCPU in a lot of projects,
while they only support building for x86. This fixes command-line msbuild
support.
TAS: Get Mysql.Data library with NuGet
Libraries: Remove WifiRemote from LICENSE.txt, we don't include it anymore

WifiRemote is downloaded in the installer nowadays.
Solution: Get rid of unnecessary references in Interfaces projects
Solution: Add nuspec files to all interface projects

Also add a script to build all the NuGet packages
Tests: Get xUnit.net with NuGet
WSS: Omit Content-Length header for live TV streams (fixes #317)

We can't know the length for live TV streams, since we're reading from a
timeshifting. Unfortunately, GetFileInfo() still returns a size, since the fileinfo
is based upon that of the tsbuffer file. Returning this wrong value (which is
usually just a few hundred bytes) caused problems with clients and browsers,
who disconnected from the stream after reading just a few hundred bytes.

Thanks to CC84 for analysis on this issue.

See the discussion in #394 for more details.
WSS: Fix exception in GetStreamingSessions

When a stream has been initialized but not started yet, the media information
isn't available yet, so don't try to access it.
Social: Log username and error message if configuration is incomplete

Yes, I've seen logs with incomplete configuration... Not sure how this can happen?