[JENKINS-21230] Broken HTML code on results page

- Element <tfoot> should not be inside <tbody>, optional <thead> is missing.
- <tfoot> moved from <tbody> directly to <table>.
- <thead> element added.
- Total number of lines in the footer extended by total number of files and total number of folders.
- Total number of languages can't be added because sorting using this column would stop working. String sorting is probably incorrectly changed to numeric sorting in such case.