Draft implementation of list submissions

Draft implementation of list submissions

This implementation works only with OBS using osc API. It lists all
home:prerelease:* projects as a submissions and gets status from OBS and
from jsoned meta data, stored in description of OBS projects.

Information about groups is taken from special OBS project
home:prerelease:groups, which also holds information in jsoned form in
project description.

Fixes: #1097

Change-Id: I1fe61f755d4397c688888ce5156cbdfe1ca03e9c
Signed-off-by: Ed Bartosh <eduard.bartosh@intel.com>
Reviewed-on: https://otctools.jf.intel.com/review/5840
Tested-by: OTC Tools Tester <ed.bartosh@linux.intel.com>
Reviewed-by: Hasan Wan <hasan.wan@intel.com>