Web UI: Select default languages in dropdowns

Try to select by default the 'en' source language (if present) and also
try to select the browser preferred language as target language (if
present).
Web UI: Just hide the table headers and not all the table
Web UI: Add spinner
UNDO
IN PROGRESS:        Add command to create blank DB
UNDO    Do proper commits for all these changes
UNDO    New web UI notes. Do commits.