Fix OS related grains on openSUSE and SUSE Linux Enterprise
Fix OS related grains on openSUSE and SUSE Linux Enterprise

Starting from openSUSE 13 and SUSE Linux Enterprise 12 the file
`/etc/os-release` is part of these distributions. Future releases are
also going to drop `/etc/SuSE-release`.

The presence of `/etc/os-release` prevents the execution of the code
parsing `/etc/SuSE-release`, leading to missing/wrong grains.

Without this code on a SLE12 SP1 machine salt would produce these
grains:
  * osrelease: 12
  * oselease_info: [12]
  * oscodename: x86_64

With this commit the following new grains are set:
  * lsb_distrib_codename: SUSE Linux Enterprise Server 12 SP1
  * lsb_distrib_release: 12.1

Moreover the following grains are properly set:
  * osrelease: 12.1
  * oselease_info: [12, 1]
  * os_codename: SUSE Linux Enterprise Server 12 SP1

Signed-off-by: Flavio Castelli <d1035a58d87d0b7918844ad2fd699273faf2f5d5@suse.com>

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt