First commit, basic infrastructure

- creation of database tables
- loading notification state
- enabling/disabling notification from the query result screen
Merge branch 'master' into features/update_notification
intermediate commit
intermediate commit, some possibilities for comparing changes
intermediate commit
rename query_update_notification to query_subscription
Updates to send properly formatted html mail

Add dependency on HTMLMail, modify the html so that it is properly displayed in gmail.
Implement editing of notification settings + some refactorings

* Add some more links in generated email
* move QuerySubscription into its own file
* enable htmlmail and mime modules in drupalpull.sh
* implement handler for editing notification settings
Merge branch 'master' into features/update_notification
Edit query_interface theming function to remove fixed ordering of all items.

Also some comments
Make query_subscription compatible with query_interface, update email for new requirements

Also several refactorings.
Minor refactoring, documentation, add link to study

include link to study in notification mail
Merge remote branch 'origin/master' into features/update_notification

Conflicts:
	drupalpull.sh
enable query_subscription in drupalpull
Enabling new query interface (SESIDEV-2) by default in drupalpull.sh
Added a feature to store an association between variable and taxonomy
lowercase boolean constants
minor refactor
Merge branch 'master' into features/update_notification

Conflicts:
	drupalpull.sh
Handle offline Opal server in query subscriptions

- Catch error from an Opal server being offline, if so report it and continue with the next subscription instead of throwing the error up to
the cron handler.
- Also check the sum of changes for being over the threshold, not just individual per-connection values.
- Store the sum of matching values in the database instead of recalculating it every time, to simplify the code.