Allow to set arbitrary Integer values to FetchSize

[PHaroZ]

Hi,

I would use rxjava2 with a mysql database to stream a huge amount of records, so I need to set fetchSize to Integer.MIN_VALUE as explained in davidmoten/rxjava-jdbc#79 but it does not seem possible right now.

Is it a choise that this feature is not kept back from rxjava-jdbc ?

Thx