Fix (Communicator): Prevent downloadCompleteQueue from leaking into window scope

This change closes a bug where the `downloadCompleteQueue` was getting leaked
in to the window scope. To fix this, a reference from `self` was changed to
`this`. Since it was tied to clearing the caches, this fix doesn't introduce
a backwards incompatible change.
minor changes to #309/#310, removed tests that fail due to phantomjs variance
Merge pull request #310 from Jakobo/dlcq_309

Fix (Communicator): Prevent downloadCompleteQueue from leaking into window scope