Copy idm_ci.py to nexus.py to make it general.
Rename IdM_CI.png to CI.png to make it general.
Update README.rst by replacing traces of idm_ci to nexus.

Signed-off-by: Gowrishankar Rajaiyan <gsr@redhat.com>
Merge pull request #35 from gsr-shanks/dev

Copy idm_ci.py to nexus.py to make it general.