Addresses issue 131

In ephys neuron searches, fixes spacing between parameter and what would
be its subscript.  Also corrects problem with no units displayed for AP
width.
(addresses issue 132) - weighted averages now displayed in ephys matrix and on neuron pages; also implements hover box
Weighted avgs displayed (addresses issue 132); ephys search fixed (addresses issue 131)
Remove extraneous code in help.php (addresses issue #3)