Drop unused pdns-backend-mongodb.prerm file
Update schema migration files for 3.3.1

In the case of MySQL, this includes the migration up from 3.0!

Git-Dch: full
Update changelog for 3.3.1-4 release
Build tests in verbose mode
Explicitly build with bind backend

Previously, bind backend was always built.
Update schema files for 3.4.0
Stop installing lib*backend.a