add cleaning option before start tests. If deleteDatabase not implemented (chromium 16), we use a random database name
add cleaning option before start tests. If deleteDatabase not implemented (chromium 16), we use a random database name

superfeedr/indexeddb-backbonejs-adapter,superfeedr/indexeddb-backbonejs-adapter,zawaideh/indexeddb-backbonejs-adapter,zawaideh/indexeddb-backbonejs-adapter