Fixed tags and added Overdue, Today and This Week to email report
Also prevented export-html.py from tripping up when no tasks are returned by a query (oh, the good times...)
Updated email report
* Added "Next Week"
* Removed taskwarrior's built in "eow" in favour of shell variables (more accurate)
* Returns "No matches." if there are... no matches.
* Different report at the weekend (only show "This Weekend" and "Next Week")
Merge pull request #1 from pearswj/master

Updated email report and fix for tag formatting (Thanks pearswj!)