Minor tweaks and fixes. Prelim adding marker

index.html
========
Merge changes from Chris
A bit of adding markers (still needs to be worked out properly)
Show edit and delete links for people with access (yet to check for
admin access on server side)
Think fixed redraw and centering issues on listing_detail page (set
center and do a refresh)
Change delete page to a dialog
Changed edit / delete links to buttons
Change shares to a collapsible div
Add debug flag for console.log output
Add logout function

Non index.html
============
Add constant for ANONYMOUS user in bootstrap
Add error messages to
delete/update_resource/add_listing_comment/add_conversation
Add user_id, edit, delete to get_markers.php response
Add user_id in is_logged_in.php response
Add server side checking for updating resource
Fix docs/help.html image URL