Added CreateField<TField> that converts to the target field type. This enables setting properties programmatically.
Fixed AddContentTypeToList by reducing code to call existing methods
Replaced SecureString creation with existing code method.
Merge branch 'master' of https://github.com/OfficeDev/PnP.git
Consolidated CreateField method to have one base internal method.
Merge branch 'master' into dev

Conflicts:
	OfficeDevPnP.Core/OfficeDevPnP.Core/Version.txt