Merge pull request #126 from devlead/nugetsourcetests

Added tests for NuGet RemoveSource and sensitive sources.
Fixed build script to get output in the AppVeyor console.
Added solution & project parsing, bugfix CakeBuildLog & refactored AssemblyInfoParser
1. Added Support for MSBuild solution file parsing
2. Added Support for MSBuild project file parsing
3. Fixed bug in CakeBuildLog of args contained {x} log would crash as Console.Write assumed to be format string
4. Refactored AssemblyInfoParser into new location/namespace Cake.Common.Solution.Project.Properties