Added 'bootable volume' filter for non-admin user

Added 'bootable volume' filter for non-admin user

During launch instance from Horizon, if non-admin
user selects volume as source for launching
instance, drop down list for volumes will also
show non-bootable volumes. It is wrong behaviour.

To fix this, 'bootable volume' search filter is
enabled so that only bootable volumes get
displayed in drop down list of volume.

APIImpact

DocImpact:Need to add bootable against
query_volume_filters in OpenStack Configuration
Reference

Closes-Bug: #1524450

Change-Id: If5bfbd73bbe02b13b76d7169ea16424493ac5fca