Add a simple backtrace for database errors when JOINDIN_DEBUG
implementation of the deleteTag method to remove a tag from the event
Merge branch 'master' of https://github.com/joindin/joind.in
Escape talk title on talk item page [JOINDIN-302]
Make sure db initialization is done only once
Merge branch 'debug-db-error-backtrace'

codesniff fixes
joindin-304: Added validation to the slides link if a url is provided
require the user to provide a full url including the url scheme (http, etc).
Merge branch 'master' of github.com:joindin/joind.in
Fix codesniff
Merge branch 'master-mfrost503' into mfrost503-joindin-241
Merge branch 'mfrost503-joindin-241'
Escaping some outputs to prevent or cause XSS to be more difficult.
Merge branch 'escape_xss'
Codesniff fixes
Merge branch 'joindin-304'
Merge branch 'master' of github.com:joindin/joind.in