eSessions.php basic functionality implemented

eSessions.php allows viewing sessions by experiment, viewing all
sessions (default), editing sessions, and deleting sessions.
eExperiments.php integrated with eSessions.php

There is now a dropdown on experiments that will load all sessions via
eSessions.php for a selected experiment.

Also made some bugfixes and began implementing the "add experiment"
function. The form is made but the handler is unfinished. There is no
link to this new functionality yet.