Migration for detector fields
Migration for detector: height added
Changed alfa to alpha
Models in Migration updated
expand length of charfields

Not tested on local database!
Changed max_length postalcode

If south migration 0008 (see commit 8997e23) is executed longer
charfields are possible
Improve admin display for Detector HiSPARC
Update migrations

Define the new detector location fields as new rather than renamed
Fix change length postalcode (allow empty pobox/pobox_postalcode)
Merge branch 'detector_migration'

Update the detector fields to use polar coordinates
Also increases the length allowed for postalcodes