Increase volume creation max waiting time

In some cases waiting 60sec, is not enough for cinder volume to be created.
For example, a 20Go LVM volume (hosting a Windows Image) would take 100sec
to be copied assuming a 200Mo/s cinder volume backend.

Issue has already been discussed in I6bcd395a where a config option was
rejected.

This patches raises the max timeout at 180sec.

Change-Id: I7e739fc20af0ae963269459b5e224c4a8b7bb87d
Partial-Bug: #1253612
Partial-Bug: #1272076
Merge "Increase volume creation max waiting time"