Description of problem:
When RHSM registration or subscription fails, we should provide at least name of the log where to investigate or othervise be more user friendly.

In my case I have provided wrong username in answers.txt and installer failed with just:

  * RHSM Registration.
  There was a problem registering the satellite.  Exit code: 70


Version-Release number of selected component (if applicable):
Compose from Thu Nov  3 11:00:56 EDT 2016


How reproducible:
always


Steps to Reproduce:
1. Run installer from answers.txt with incorrect rhsm username specified there


Actual results:
# /tmp/media.mnt-TucEaz/install.pl --answer-file=.../answers.txt --non-interactive --run-updater
* Starting Red Hat Satellite installer.
* Loading answer file: .../install/answers.txt.
* Performing pre-install checks.
* Pre-install checks complete.  Beginning installation.
* RHSM Registration.
There was a problem registering the satellite.  Exit code: 70


Expected results:
We should point to /var/log/rhsm/rhsm.log or /var/log/rhn/rhn_installation.log if it contains more info


Additional info:
IMO this "user friendliness" might be important because with this some admins might be hitting RHSM space for the first time.