Make clean_with work for multiple db connections
Make clean_with work for multiple db connections

clean_with avoids using strategy= so that it doesn't actually change the
strategy. This means it was bypassing the section that set the database
to actually clean and therefore it was always cleaning the default.

HaiTo/database_cleaner,0xCCD/database_cleaner,yangc5/playlister-sinatra-v-000,glebtv/database_cleaner,reinaris/database_cleaner,DatabaseCleaner/database_cleaner,amorphid/database_cleaner,yangc5/playlister-sinatra-v-000,claptimes5/database_cleaner,yangc5/playlister-sinatra-v-000,awilkening/database_cleaner,ericraio/database_cleaner,yangc5/playlister-sinatra-v-000,yangc5/playlister-sinatra-v-000,avalonmediasystem/database_cleaner,simonmorley/database_cleaner,yangc5/playlister-sinatra-v-000,fajrif/database_cleaner,custora/database_cleaner,yangc5/playlister-sinatra-v-000,eliotsykes/database_cleaner,DatabaseCleaner/database_cleaner