Added more configurations to the project for targeting multiple
framework versions and building all configurations at once.
Support for .NET 4.0 was added relatively easily. Only
System.Threading.Timeout.InfiniteTimeSpan was missing. I replaced it
with the equivalent member of vProto.BaseClient.InfiniteTimeSpan.
.NET 3.5 support isn't planned yet. The lack of tasks and such breaks
RMI almost completely. It won't happen until I can be bothered with a
workaround.
Assembly configuration now reflects the target framework used as well.
Also, more useless using statements were removed and now the vProto
project only depends on mscorlib.dll and System.dll.

Repository now also includes binary distributions of vProto for every
framework targeted and every configuration. Debug assembles are named
accordingly. PDB file is also included for eventual debugging needs.
The available binary files are also signed with a key so they can be
used anywhere and have their identity maintained. (This also mans you
may have to do one extra step to build the solution)