changed all references to the native code library to be cross platform
Maybe make this work better with mono...
Merge remote-tracking branch 'upstream/mono' into mono

Conflicts:
	libsodium-net/CryptoHash.cs
	libsodium-net/GenericHash.cs
	libsodium-net/OneTimeAuth.cs
	libsodium-net/PublicKeyAuth.cs
	libsodium-net/PublicKeyBox.cs
	libsodium-net/SecretBox.cs
	libsodium-net/SecretKeyAuth.cs
	libsodium-net/ShortHash.cs
	libsodium-net/SodiumCore.cs
	libsodium-net/StreamEncryption.cs
MonoDevelop removed some project settings when I first opened it, even though it handles them just fine.  I added them back.
made the unit test project loadable by MonoDevelop, and converted to the tests from MSTest to Nunit.
updated README to make mention that the library can now be compiled with Mono
Merge pull request #2 from jestin/mono

Merge of upstream changes and conversion of unit tests
Add NUnit project file
Make NUnit version agnostic

This may break for drastically different versions of NUnit, but it's the
only way I could get it working on my machine, without just setting it
to another version number that will break it for other people. This
works fine in VS, does it work for mono?
Merge pull request #3 from adamcaudill/mono

Add Mono Support