Participation is now polymorphic.

Both a member and a user can belong to an instance of Participation,
which basically means that both members and users now can participate to
an presentation.
Merge branch 'master' of github.com:Samfundet/Bedpres into polymorphic-associations

Conflicts:
	app/models/user.rb
	db/schema.rb
Notification can now belong to a Member.
Added ordering to User/Member #notifications.
A users notifications is destroyed with the user.
Change the way email validation is skipped.

Email validation is now not simply skipped during non-production mode.
The reason for this is that we actually want to test sending of emails.
Instead, one can call #skip_email_validation! on a user object before
saving it.
Testing email confirmation.

We now require users to verify their emails before utilizing the system
and the tests obviously need to reflect this. This adds test coverage
for email confirmation.
Merge branch 'master' of github.com:Samfundet/Bedpres into polymorphic-associations

Conflicts:
	app/controllers/participations_controller.rb
	app/models/participation.rb
	app/models/presentation.rb
Only show notifications if actually logged in.
Bunch of variable renaming.
More consistent word convention.

The Then step said 'Then a user named ..', so I thought the Given step
also should say 'Given a user named ..'.
Step definitions for attendance supports members.
Adding participation tests for members.
Frontpage notice upon no upcoming presentations.
Merge branch 'master' of github.com:Samfundet/Bedpres into mobile

Conflicts:
	app/views/layouts/application.html.haml
	app/views/presentations/_presentations.html.haml
	app/views/presentations/index.html.haml
	app/views/presentations/show.html.haml
removed references to user and replaced with participant
moved create presentation link outside of conditional
removed reference to user_id and annotatet model
renamed user references to participant