Revert back to non-join total marks

Joining was too slow.  3.4 seconds, had to examine 20,000 records compared to a few hundred this way.
Only install/uninstall configured plugins

Don't look at the installed plugins file... otherwise we might be missing the example plugin which is required for testing
add a test for the `ForScanAndMetric` hot spot record list
comments!
Use a join, make it faster and more readable
Revert "Use a join, make it faster and more readable"

This reverts commit 5f25fe92d72e953a174707c554cd18e07541152f.
Does not return the correct number of marks for the most recent page scan
Improve the query by using a JOIN

data should not be filtered in the SELECT clause, so use a more efficient join.
Merge pull request #72 from mfairchild365/pass-fail-hotspots

Improve performance of Pass fail hotspots