avoid overwriting a modified ceph.conf without --overwrite-conf

While we're at it, continue with mon/osd/mds creations if there is a
failure, but return an error at the end.

Signed-off-by: Sage Weil <sage@inktank.com>
lsb.py:  Update for rpm based systems

lsb_release returns multiple fields seperated by newlines on some
platforms and spaces on others. Get release, version, and codename
fields individually instead of using a single request.

lsb_release is not installed by default on some system.  Check if
it's present before calling.  This allows a better error message.

Signed-off-by: Gary Lowell  <gary.lowell@inktank.com>
install.py:  Remove gdisk from the install list.

The gdisk (or gptfdisk) package is now listed as a requirment
for the rpms.  No need to explicitly list it.

Signed-off-by: Gary Lowell  <gary.lowell@inktank.com>
install.py:  update for rpms

Change centos to CentOS for the release name.  Update the path
to the ceph-release rpm to match the dev repos.

Signed-off-by: Gary Lowell  <gary.lowell@inktank.com>
Merge remote-tracking branch 'gh/wip-rpm'

Reviewed-by: Sage Weil <sage@inktank.com>