Refactored ManifestDigest
Improved exception handling

Closes #80
Updated NanoByte.Common and SharpZipLib
Introduced FeedUri class

- Replaced InvalidInterfaceIDException with UriFormatException
- Renamed FeedID properties and arguments to FeedUri
- Renamed InterfaceID properties and arguments to InterfaceUri
Refactored unit tests

Added unit tests for SelectionCandidateProvider
Added declarative way of providing local feed overrides

Closes #82
Installer: Install .NET Framework 4.0 instead of 2.0
Replaced LinqBridge with .NET Framework 3.5
Switched NanoByte.Common to .NET 3.5