Cleanup: coding style fixes
`mtime` refers to the submission, not to the unit

Dejá vu of 5e26306.
Perform calculations in seconds
Cleanup: removed unused imports
HACK: get the main page to show
HACK: get progress bars to show
HACK: Get progressbars to show in the main page
HACK: Fix progressbar in language pages
HACK: Fix table zebra coloring
HACK: Fix project progressbars in main page
HACK: just set item.stats to True

We now only use it in _table_row.html to determine whether the table
shows stats or not.
HACK: This tooltip is not used
HACK: Make this work after turning 'stats' into bool
HACK: Update goal code similar to

6a4c6bd66948f907666d4d1374453e1dc110e436
HACK: pass an item.code for goals

Still not working
Kill more unneeded get_stats
Fix sort key in the front page
We can do without filtering out language with 0 translations
Update project summary using AJAX
Unused import