Added Roslyn and F#

Roslyn and F# are both high profile open-source projects targeted at .Net developers. I don't see any reason why they should be omitted from this list.
Merge branch 'patch-2' of https://github.com/svick/dotnet into svick-patch-2

Conflicts:
	dotnet-developer-projects.md
Merge branch 'svick-patch-2'