common: add trailing newline before parsing cfg

common: add trailing newline before parsing cfg

Ceph fails to parse config files that lack a trailing newline.
This mainly affects Windows, where text editors won't add one by
default.

This issue has been addressed by a previous commit [1] but that
code path is no longer reached [2][3], so we need to go down a level.

[1] 3b590314ac49b955b2123f03f4c4417e5534ec98
[2] http://paste.openstack.org/raw/800153/
[3] https://github.com/ceph/ceph/commit/e7dcc403b20922ffeeca114899f90a385bf25f0e

Signed-off-by: Lucian Petrut <lpetrut@cloudbasesolutions.com>