doc auto extract archive and bulk delete middleware

Grizzly added these two new features. Add sections to the
'additional features' section of the object storage admin guide

patchset2 fixes grammar - thanks Diane!

fixes bug 1089189

Change-Id: I939267ecf189ff0abbe1f135d22b6b3a6f24dd6a
Merge "doc auto extract archive and bulk delete middleware"