Fix #1132

Fixes #1132.  Seems the trick was to copy the ```name = opts.name || backend.name``` logic from the ```Pouch``` constructor (pouch.js line 29) to ```destroy()```; otherwise ```_pouch_{{dbName}}``` would always override ```{{dbName}}```.

Also sneaking in a commit to fix a few typos in the documentation, unless I misunderstood something.