Pass all identity headers received to glance

There is an upcoming patch in nova which passes identity
headers to glance client. We want to ensure that these get
passed to glance, which in turn with help the no auth
option in glance.

Resolves bug 1200761

Change-Id: Ifbef582aa4e64a2e7a46db43a9cc6cf8c3531dbd
Increase default page_size value

This is a temporary solution. Increasing the default page size (which is being
used everytime, since the client is ignoring nova's --limit param). This should
decrease the number of queries that glance does when nova requests an image
detail list.

Bug 1200257

Change-Id: I7ed4521698570cbae9c20e69ddca8b11b57c65ad
Merge "Pass all identity headers received to glance"
Merge "Increase default page_size value"