Add support for non-string types

[tabakerov]

This function right now doesn't support non-string types.
So if I do dotnet saturn gen Post Posts id:string title:string body:string is_published:bool I'll get errors at li [] [ strong [] [rawText "Is_published: "]; rawText o.is_published ] (and some similar errors around) where rawText is expecting string and not bool so I need to do .ToString() conversion.

[Krzysztof-Cieslak]

Yes, I think in general the generator tooling was tested only on strings - it was not really a huge priority for me so far.

Adding support for different types is important for couple of places - generated views, mockup validaition layer (checking isNull on value type [boool, int etc] won't work], and migration scripts (where types passed to generator should be transformed into appropriate DB types [ and this probably should depend on the DB that is used, but adding supports for more DBs is something for seperate issue ;) ] )