Fix Storage Backend Wording

The previous wording was confusing, the config setting does not
configure the *only* glance backend but the *default* glance
backend. You can still overwrite it per image, and searching
for glance images involves all configured backends.
Merge pull request #132 from dirkmueller/default_store

+1
Merge pull request #134 from jtwill98/pull-req-release-roxy-master-17620546f850dd64dddb20c9c812824cc5589804

Merge of Latest Pebble commits into Roxy [7/13]
Merge DE1227 - Move Pull from source to the bottom of each proposal
Move Pull from source to the very bottom of attributes section and add section heading to follow pattern set by community
Add qemu-utils dependency for glance
Merge pull request #138 from arkadykanevsky/pull-req-release-roxy-master-a1820b252d31a11dc14ee350ee45c2856bab8b27

+1
Merge pull request #135 from dpaterson/pull-req-release-roxy-master-b90303f1b8633b6994845dfa3cc3ee1862be2f9e

https://github.com/crowbar/barclamp-glance/pull/135

Merged by devtool for ArkadyKanevsky