[rpm] Add Sha1header to the output of 'installed-rpms'

RPM meta data is useful for identifying 3rd party packages present on a system.
This patch adds the Sha1header column to installed-rpms.
Sha1headers identify uniqueness of installed RPM with rpm tag

Signed-off-by: Poornima M. Kshirsagar <pkshiras@redhat.com>