Add csv as a source data format

[Motorrat]

CSV is a bit tricky because it does not have data type metadata. So in order to take that in we will have to guesstimate that or get this metadata in some other way. The default way would be to as the user to specify this information but then it won't be "zeroconf" anymore. One way of approaching this would be https://github.com/bashalex/datapot