ensure that api-paste.ini does not contain the auth_token

Since commit 70798fb2624 removed the api-paste.ini template from chef, systems which already had it installed by chef would keep the old version because it was modified outside of rpm. But these files contained the auth_token middleware configuration which would conflict with the one from cinder.conf.

This commit fixes that problem by making sure to overwrite api-paste.ini
with a vanilla file from the git repository (current stable/icehouse)
Merge pull request #192 from mapleoin/re-add-api-paste

ensure that api-paste.ini does not contain the auth_token
Switch to thin LVM backend by default

This provides first of all significant more performance
for volumes about snapshots (thick snapshots turn every write
on the volume to a sync+flush for the snapshot), and saves disk
space at the same time. Furthermore it avoids hang issues
with the SLE11 lvm (which does not have lvmetad enabled and hence
rescans the lvs on every command).
Merge pull request #193 from dirkmueller/master

Switch to thin LVM backend by default