Adds tasks export script for swift store

partly implements bp async-glance-workers.

The executor design is still in discussion within the community. And,
we wanted the export feature to be available for general access, so
this is available internally.

Change-Id: Ia24a81ccd136f7dfc885860208339602d52dbe5a
adds image.get_data and store.get

added SwiftStore class to script utils

Change-Id: Ie9313043377cfc07fc80822a5c91c672482ebbce
pep8 fixes

Change-Id: Ifa55ee551fdec2accf05bf02d2f13b93fdd1ade2
More tests and xfer data

Change-Id: Ie996201d70cbbbda64762632ddb7e51efbe1e400
refactor

Change-Id: Ib2332e20dff2ca1a97a63757467178c444a74dd5
cooperative reader

Change-Id: I24342e63334eabf46adab4a80f0d2350f4e42c33
add export filter

Change-Id: Iaa9e739884d3798ffeb302660603140ca1df3ab9
better error handling

Change-Id: I0e24a38b8eedbb595f403c5ec8113142c1028188