autotest-scheduller: add the dependency on mysql to the systemd service file

After a fresh install of autotest from next, I tested a new feature of arc:

$ arcli server -s
Concerns: Yes
Scheduler Running: No
Scheduler Watcher Running: Yes
Install Server Running: No
Log Disk Space Usage: 18%

Running `systemctl status autotestd` would show:

_drone_manager.shutdown()
AttributeError: 'NoneType' object has no attribute 'shutdown'
Traceback (most recent call last):
File "/usr/local/autotest/scheduler/autotest-scheduler", line 13, in <module>
monitor_db.main()
File "/usr/local/autotest/scheduler/monitor_db.py", line 279, in main
main_without_exception_handling()
File "/usr/local/autotest/scheduler/monitor_db.py", line 272, in main_without_exce...andling
_drone_manager.shutdown()
AttributeError: 'NoneType' object has no attribute 'shutdown'

Turns out that the autotestd was trying to start before the MySQL
database, which is hard dependency.

After this patch, arcli is happy about the server state:

$ arcli server -s
Concerns: No
Scheduler Running: Yes
Scheduler Watcher Running: Yes
Install Server Running: No
Log Disk Space Usage: 18%

Signed-off-by: Cleber Rosa <crosa@redhat.com>
server.hosts.remote: When install server is not available, retry

Rather than giving up and throwing a hard to understand
exception to users when the install server code can't reach
the install server, retry every install_timeout / 100 seconds.

If after install_timeout / 10 we still could not reach
the server, then throw an easier to understand error
(Could not contact the install server).

CC: Rudá Moura <rmoura@redhat.com>
Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #742 from clebergnu/autotestd_service_dep

systemctl autotestd service file dependency
install-autotest-server.sh: Add support to install on Debian.

Signed-off-by: Rudá Moura <rmoura@redhat.com>
web frontend: Use django.contrib.staticfiles to deliver static content

frontend.wsgi now delivers both static (/media/) and dynamic content,
by using django.contrib.staticfiles.handlers.StaticFilesHandler and
STATIC_URL setting, so we can remove ADMIN_MEDIA_PREFIX due its deprecation,
starting from Django 1.3. Fix issue #743.

Signed-off-by: Rudá Moura <rmoura@redhat.com>