A cron job to fix parameter values' discrepancy.

Part of #136.
Merge remote-tracking branch 'upstream/master' into solvers_num
Reacting to code review (part of #136.)
Merge remote-tracking branch 'upstream/master' into solvers_num
Fixing empty last page in attempts list

in "Review" tab.

Fixes #152.
add pdf.min.js
delete unused files and directories under /static/pdfjs
Merge pull request #189 from anubhavsinha/#187_pdfjs_minified

add pdf.min.js
Merge pull request #183 from egor83/152_other_subs_last_page

Fixing empty last page in attempts list in "Review" tab. (fixes #152)
Merge pull request #172 from egor83/solvers_num

Fixes #136 - number of solvers for a challenge is calculated incorrectly