Target .NET 4.5.1

[walro]

Close #21.

[walro]

I'll try get Travis in too.

[walro]

I'll try get Travis in too.

It's troublesome for these reasons:

• We pre-generate the serialization assembly with sgen.exe (sgen is available in mono), we need to write a smarter post build event or skip it completely.
• We are testing with MSTest which is not supported by mono, porting to NUnit should be fairly straight-forward though.
• We are create a NuGet package on each build (also a post build event), using PowerShell which for obvious reasons will not work :)

I'll create follow-up issues concerning these things.

[walro]

I'll create follow-up issues concerning these things.

#20, #23, #24