(#44) - Fix worker tests for alt backends
(#1992) - fix attachment uploads in Android 4.x
(#2132) - disable local Web Workers in IE
(#2164) - longpoll ajax timeout issue
(#1661) - use task queue for IDB for IE

Adds a task queue for all create/destroy
operations on IDB databases, because apparently
IE 10 and 11 can't function correctly if there's
any overlap between any destroys/creates (even
from different databases).

Also apparently you can't have two databases
with the same name open at the same time,
so we have to cache this.
(#2064) - Show error message in saucelabs failures
(#2202) - skip migration tests in IE
(#2198) - temp workaround for IE10 console.trace
(#2185) - test in IE 10
(#802) - adding purge
refactor