Append the erratun number when doing a request to add an nvr to errata
Add more params to 'add to errata' and add cronjob_mode

Params added to 'add to errata': tag, erratum

tag is really 'target_tag' in the tasks view.

Cronjob Mode is used to intentify which modes from the cronjob are available for
each distro.
Merge pull request #143 from thescouser89/cronjob_modes

Cronjob modes