Calling preupgrade-assistant API directly

(cherry picked from commit a56bf742ce75fd03ea9c0a72bcfb7aee01533127)

Related: rhbz#1059447
Revise how preupgrade issues are printed

(cherry picked from commit 33b00ca07cfe03d0b167aed94313e6145925b18c)

Related: rhbz#1059447
New version 0.7.10
Save the repo config files to /var/tmp/system-upgrade/yum.repos.d

Resolves: rhbz#1080966
New version 0.7.11
Fix a changelog typo
Add an option --cleanup-post to cleanup packages in post scripts.

Resolves: rhbz#1070603
Add a Requires for a sufficiently new yum

Resolves: rhbz#1084165
Disable screen blanking

Resolves: rhbz#1070112