Ensure uniqueness of generated IDs
Ensure uniqueness of generated IDs

Refs #16

kilbot/IDBWrapper,mizchi/idb-wrapper-promisify,mizchi/idb-wrapper-promisify,jensarps/IDBWrapper,jensarps/IDBWrapper,GerHobbelt/IDBWrapper,rubenstolk/IDBWrapper,kilbot/IDBWrapper,rubenstolk/IDBWrapper,jayfunk/IDBWrapper,jayfunk/IDBWrapper,safetychanger/IDBWrapper,safetychanger/IDBWrapper