some tests for the new mon_errors check

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
create a helper for a safe get on ConfigParser

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
add a check to catch common monitor deployment errors

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
[6348] ceph-deploy should use same option seperator

define subclass for Ceph config files.
make new.new and conf.load use new CephConf
add test case for config writing.

Signed-off-by: Andrew Woodward (awoodward@mirantis.com)
Move try: cfg.get excepts to CephConfg.safe_get

move safe_get from config to conf.CephConfig
update existing uses of safe_get
move try: ... except to cfg.safe_get
remove not needed imports

Signed-off-by: Andrew Woodward (awoodward@mirantis.com)
Update catch_mon_errors and tests

change mon_initial_members test in mon.catch_mon_errors to be able to catch
 None result correctly
add second test to test_mon to ensure both None and not hostname in ..
 are tested

Signed-off-by: Andrew Woodward (awoodward@mirantis.com)