Some maybe useful commits

[raymontag]

Hey,

during my work with DiOS I applied some changes which were really useful for me and maybe you think it's useful, too.

Changes:

• Handle old ideviceinstaller versions, too. I work in different environments, some with the old 'uuid-version, some with the newer 'udid-version'.
• Print the job ID when a job is scheduled with scheduler.py. I needed it for a scraper which schedules hundreds of jobs in DiOS and gets updates from the jobs via the job URL.
• Choose the job type with scheduler.py instead of run_app only.
• Instead of setting a job to the failed state if the minimal needed iOS version is not matched the job is set again to pending. The database has a field which remembers the minimal version from the first try. After this is done the backend gives the job only to devices which fit the requirements.
• I introduced a field for error messages of failed jobs. Is useful to see what the problem was without scrolling through the logs.
• Choose User-Agent by the device class (iPad, iPhone, iPod). If an install job cannot get app informations from the iTunes store this is probably the case because the app is e.g. a iPhone app but the device is an iPad. Therefore the backend remembers which device types already tried the job. The job will fail only if getting the app informations worked for none of the three device types.

The pull request for the Backend repository is needed for some of these changes.

[raymontag]

I found one or two bugs in these changes. I will fix this the next days.

[msk521]

Can this project still be used now？