`volumes` add/remove common directory

[tomaszmrugalski]

Right now all the files have IMAGES/ prefix, e.g. IMAGES/RJAC/2017Q2/SFDB_2017-06-26_23-36-30_J038173_RJAC_SI_1x1_0300s_NGC 4565.fit. However, they're not stored in IMAGES dir anymore. There should be a way to remove prefix from all frames.

[tomaszmrugalski]

Done this manually using direct sql query. Not great, not terrible.