Install Guide: Fix bugs in block storage node

* Fix misspelled pvcreate command
* storage node needs cinder database password
* tgtd.conf must include cinder volume configs (rhel;centos;fedora)
* lvm filter wouldn't work with the volume used

Change-Id: Iaa81520541e5b4d98601d81998e67322c069f91d
backport: havana
Closes-Bug: #1243671
Merge "Install Guide: Fix bugs in block storage node"