Use longform arguments to pg_dump for better readability
Pass --create argument to pg_dump to drop/recreate the DB at the
beginning of the dump

This should solve an issue where if you create a new table Foo on a
branch, then switch back to master, Foo continues to exists as the
"--clean" argument didn't know anything about Foo when master was last
dumped, so there's no command to drop the table. Foo thus live on in the
master DB, even though it was new to the feature branch.
Update MySQL dumping to also drop/create the database

This makes sure new objects (ie tables) that are added in a feature
branch are dropped when switching branches, otherwise the dump only
drops the objects that it knew about when it was dumped.
Terminate connections to the PG database before restoring and
drop/create the database ourselves since structure.sql wont have the
commands to clean/create the database