New Feature: Upgraded integrity check - checks for redundant tables a…

…nd gives option to delete them

Dev notes: This is specifically to allow for removal of old_survey and old_tokens tables that are leftover after deactivating a survey. It allows users without direct db access to capacity to clean up their databases a little.

git-svn-id: file:///Users/Shitiz/Downloads/lssvn/source/limesurvey_dev@7306 b72ed6b6-b9f8-46b5-92b4-906544132732