Refactor handling of warnings

Related to #94.

Signed-off-by: Martin Milata <mmilata@redhat.com>
Signed-off-by: Jakub Filak <jfilak@redhat.com>
Add support for parsing /etc/os-release

Actual parsing code taken from libreport, originally written by Jakub
Filak.

Implementing the parser with callback allows reusing it in libreport without
bringing in the libreport-specific hacks and workarounds.

Related to #94.

Signed-off-by: Martin Milata <mmilata@redhat.com>
Signed-off-by: Jakub Filak <jfilak@redhat.com>
operating_system: add workaround for rawhide

Closes #94.

Signed-off-by: Martin Milata <mmilata@redhat.com>
Signed-off-by: Jakub Filak <jfilak@redhat.com>
Add cpe member to struct operating_system

See http://www.freedesktop.org/software/systemd/man/os-release.html or
http://cpe.mitre.org/ for more information.

Indirectly related to #94 - is not needed now but could be used for
searching for uReports in the future.

Signed-off-by: Martin Milata <mmilata@redhat.com>
Signed-off-by: Jakub Filak <jfilak@redhat.com>