Add Visual Basic support to AssemblyFileInfo
Optional Namespace in AssemblyInfoFileConfig

Namespace should be optional as it's not required if GenerateClass = false.
If GenerateClass is false, a namespace should not be added to the
AssemblyInfo file.

- Make AssemblyInfoFileConfig a class with optional UseNamespace
- Alter CreateCSharpAssemblyInfoWithConfig and
  CreateVisualBasicAssemblyInfoWithConfig to not write a namespace line
  unless a class is being generated
Merge pull request #471 from petersondrew/master

Add Visual Basic support to AssemblyFileInfo task and make Namespace optional in config