Add additional filter parameter to elements search

[isedwards]

Rename GET obselements/search as GET elements/search (no longer tied solely to the obselement table).

elements/search?query=${query} should also include station_id as an optional query parameter. If station_id is present then available element results should be returned from the stationelement database table for the given station instead of the obselements table list of all all element codes.

[faysal-ishtiaq]

The second part is done. I will do the renaming part tonight.