Database purging doesn't work

[jmdkastro]

Generated plots stay on the server for more than the hard-coded five minute threshold after which new queries should delete old output. I have not checked if the same is true for output tables, but this should be checked.

[keflavich]

@jmdkastro how did you determine this? It will help me find the bug.

[jmdkastro]

I generated a plot this afternoon at http://camelot-project.herokuapp.com/static/figures/Output_Sigma_sigma_r_20150618162012624428.png, then did another query 20 minutes ago (which was almost two hours later) and reopened the above link. The plot was still there. The same can be done for the table with the above ID.