gevent workers are async and reduce time out problems for pending long ajaxes

finally harmonize all date processing with DB type date and timestamp, python conversion to and from + fix job_looking_date pre-selection + add job_looking boolean to DB

fix org_type = 'others' case and refactor selectSavedMenus into setupSavedItems for future coltype date

remove user cache entirely (it works fine by itself, but the app is later run over multiple processes that have separate memory, so the cache can be updated in one process but not in another :/)

we cascade the LEFT JOIN-ed queries to ensure correct cardinality of records (probably not necessary when joining affiliations + keywords because affiliations are 1 to 1, but definitely needed when joining affs + kws + hashtags)

(not necessary it actually worked well inside docker)

This reverts commit 3daf2376.