Auto-logout on index if already logged in

Added logic so that if the user is already logged in, but goes to index.psp,
it will log him or her out.  Thinking here is that the user should never
be confronted with a page asking him/her to login if they are already logged
in.
Fixes #202
fixing issue 210
Checking in links to food diary site, fixes issue #209
fixing tab order, issue #206
more tab order stuff
fixing issue #215
Merge pull request #212 from meganap/agut_issue_210

fixing issue #210
Merge pull request #216 from meganap/agut_issue_215

fixing issue #215
Merge pull request #205 from adamrp/logout_from_index

Fixes #202, Logout from index
Merge pull request #214 from meganap/agut_issue_206

fixing tab order, issue #206
Merge pull request #213 from meganap/agut_issue_209

Checking in links to food diary site, fixes issue #209
Merge pull request #204 from meganap/agut

checking in templates for overview pages
fixing issue #210
updating fix for issue #201
Fixing issue #208
Merge pull request #217 from meganap/agut_issue_201

fixing issue #201
Fixes #211, Add participant confirmation message
Merge pull request #219 from adamrp/survey_complete_message

Fixes #211, Add participant confirmation message
Fixes #221, Fixes #222

Prevents a user from adding identically-named participants