Enable CI

[ForNeVeR]

The library should periodically build on Travis and Appveyor.

[vitalyster]

I've setup both, but appveyor can't find nunit, and travis failed on nuget restore :)

[ForNeVeR]

I see. I'll take care of them.

[ForNeVeR]

Seems I don't need to. Everything works now.

[vitalyster]

please fix dotnetcore branch :)

[ForNeVeR]

Ok, planned to take a look.

[vitalyster]

there is a project.json for .NET Core target and it works with dotnet, but it breaks msbuild which imports project.json too besides project.csproj. Need somehow ignore package.json or update it for net451 and netcoreapp1.0 both

[ForNeVeR]

Yep, I thought that ideally we'll have to produce both CoreCLR and FullCLR builds from the same project.json. Will investigate.

[ForNeVeR]

I'll return to the issue after conducting experiments in scope of xmppo/Jabber-Net#61.