Allow configuration of multiple glance stores

Glance can handle multiple stores at the same time,
we just need to allow configuring them at the same time.
Fix setup of Glance VSphere Store

When using a vCenter based store, we need the
datacenter path to be configured.
Merge pull request #229 from dirkmueller/master

Glance VSphere fixes
webui: Remove some attributes from webui

These settings are not extremely useful, so don't display them anymore.
They're still available in the raw view.

bind_open_address, image_cache_datadir, image_cache_stall_timeout,
sql_idle_timeout