Removed duplicate string.Format

Console.WriteLine 'includes' a string.Format so the string.Format inside
Console.WriteLine is not needed.
Removed missing files from csproj

In the Microsoft.DotNet.Build.Tasks there were some files which are not
(yet) checked in.
Update CONTRIBUTING.md to point to our wiki
Adding the appveyor yaml file to setup CI.
Adding appveyor status badge to readme.md
Merge pull request #15 from Sridhar-MS/appveyor-setup

Appveyor setup
Fix for building repository with spaces in root

build.cmd was failing if the repository has spaces in its path.
Merge pull request #16 from Sridhar-MS/space_in_path-fixes

Fix for building repository with spaces in root
Updated link to Strong Naming documentation
Merge pull request #17 from jozefizso/patch-1

Updated link to Strong Naming documentation
Merge pull request #13 from terrajobst/contrib-changes

Update CONTRIBUTING.md to point to our wiki
Fix incorrect link in README.md
Merge pull request #10 from yannisgu/fixCsproj

Removed missing files from csproj
Merge pull request #9 from yannisgu/removeRedundancy

Removed duplicate string.Format