Remove excessive number of configs from station 4 and 91

[153957]

$ h5ls /databases/frome/2017/4/2017_4_15.h5/hisparc/cluster_amsterdam/station_4
blobs                    Dataset {799871/Inf}
config                   Dataset {248013/Inf}
…
$ h5ls /databases/frome/2017/4/2017_4_12.h5/hisparc/cluster_amsterdam/station_91
blobs                    Dataset {399080/Inf}
config                   Dataset {121744/Inf}
…

The public database seems to crash while processing these configs (hisparc-update), or while trying to render config data (uwsgi). Those configs should be removed (keeping maybe one, first and/or last?).

The blobs could also be updated, but they do not seem to take a lot of extra space. Removing the config blob data entries would mean that other blob indexes need to be updated as well, so it is easier to simply leave that data.

[kaspervd]

See #24