Fixed typo in AssemblyInfoSpecs.cs
Added AssemblyHelper.fs which allows to get assembly version easily
Added tests for AssemblyHelper
DeployDir not needed
Updated assembly version (#423):

- Moved code to VersionHelper.fs
- Removed AssemblyHelper.fs
- Updated tests
Removed unnecessary duplication
Merge pull request #423 from Ravadre/develop

Added GetAssemblyVersion helper