Update dbSNP 147 -> 150 and adding custom Freq DB

Hi,

How to update the dbSNP version from 147 -> 150 (latest one available for Annovar) ?
Do we have to update the InterVar code ? or we can simply do it by downloading the 150 file and rename it to 147 (hack !)

Also, how is it possible to add new frequency databases (like GME) ? or custom made internal frequencies db ?

Thank you