Fixed volumes mount in case of existing volumes

Changed pattern of volumes mounting from "create all volumes,
find unmounted partitions, mount them" to "create volumes,
remember their device names, wait for specific devices (not
abstract as before), mount them". This allows to make sure that
we are mounting devices we requisted and avoid interfering with
other devices.

Change-Id: Ib2f7a801f3e45020d24a59564a102c2fd77ab525
Closes-Bug: #1326021
Merge "Fixed volumes mount in case of existing volumes"