Remove Microsoft.Build.dll dependency for Linux support

	new file:   Microsoft.Build.Evaluation/Microsoft.Build.Evaluation.csproj
	new file:   Microsoft.Build.Evaluation/Project.cs
	new file:   Microsoft.Build.Evaluation/ProjectItem.cs
	new file:   Microsoft.Build.Evaluation/Properties/AssemblyInfo.cs
	modified:   OmniSharp.sln
	modified:   OmniSharp/OmniSharp.csproj
Fix paths in unix (TODO should use MONO var)

	modified:   OmniSharp/Solution/CSharpProject.cs
Merge pull request #1 from zenakuten/master

Remove Microsoft.Build.dll dependency for Linux support