Convert to Paket - WIP

Issue #845 suggested that you are interested in [Paket](http://fsprojects.github.io/Paket/index.html) support for ScriptCS.

So maybe you are also interested in actually using Paket for the scriptcs project.
For me this is only a test of Paket's convert-from-nuget feature (see http://fsprojects.github.io/Paket/convert-from-nuget.html) so feel free to close this.

A couple of things I noticed:

1) you are using aliases (https://github.com/forki/scriptcs/compare/scriptcs:dev...forki:Paket?expand=1#diff-d7161f9565893ee73f9a081ec1cf4cadR164) - Paket doesn't have this feature yet. I created an issue https://github.com/fsprojects/Paket/issues/346
2) your test/ScriptCs.Engine.Mono.Tests/packages.config is "broken". You use more packages than listed there. I fixed that manually.
3) I had to manually remove version no.s from path. Like in the yml and batch files. But that's a good thing since you don't have to do this manually any more.
4) I remove NuGet.exe from the repo, but paket retrieves it via NuGet.CommandLine package. You still need this for creating new NuGet packages.
5) I'm not sure why the build changes common/CommonVersionInfo.cs

THis is still WIP since I don't know if it works on Travis.