Minor query terms bar ui changes

[VasilyShelkov]

• added some margins to the query terms
• added >30 chars vaidation as we don't expect nor want ussers to have this large a search
• now doesn't break if tryig to select tweet records and users when only the tweet has been inserted into the db
• now properly activate the search only db checkbox
• shows a fetching loader when fatching initial results from db

@Winwardo again for your reference

[Winwardo]

:+1: