Capitalized option conflicts with systemd ceph-osd-prestart.sh script

[Gui Maluf Balzana]

I've set
```
class { '::ceph':
  ...
  osd_crush_update_on_start => true,
}

```

Which sets the capitalized "True" on `/etc/ceph/ceph.conf`
```
# cat /etc/ceph.conf
...
osd_crush_update_on_start = True
```

On Ubuntu 16.04, using systemd, `/usr/lib/ceph/ceph-osd-prestart.sh` is executed which has the following test:

```
...
update="$(ceph-conf --cluster=${cluster:-ceph} --name=osd.$id --lookup osd_crush_update_on_start || :)"
if [ "${update:-1}" = "1" -o "${update:-1}" = "true" ]; then
...
```

If value on ceph.conf is set to capitalized True, this script will fail.

I've tried to set `osd_crush_update_on_start` value to `1` but seems like systemd scripts expects the lower case `true` value.

```
class { '::ceph':
  ...
  osd_crush_update_on_start => '1',
}

```

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/473546
Committed: https://git.openstack.org/cgit/openstack/puppet-ceph/commit/?id=28c4efee3df8eb0e7688631fe74f1d75f162702a
Submitter: Jenkins
Branch: master

commit 28c4efee3df8eb0e7688631fe74f1d75f162702a
Author: Guilherme Maluf <email address hidden>
Date: Mon Jun 12 14:49:49 2017 -0300

    Set lowercase for ceph_config values

    Capitalized values of True and False are conflicting with systemd
    scripts

    This commit set all values to lowercase

    Fixes: Bug #1697476

    Change-Id: Ibd01a7a850e7593fabd676b8b0c0af2b77101a2a