Bug 989929 - [Contacts][Refactor] Create Contacts indexed DB library to ...

...support synchronization from the Global Contacts Datastore
What about creating indexes on demand? I am not knowledgeable enough of the impact that an index has on space/general performance, but in limited devices we could just create the obvious ones and then create the index for more rare fields the first time the user searches for those (how to detect what field the user is searching for is another issue).