start removing globalize3 from notifications

This will make notifications a nested attribute of call for papers.

The globalize3 gem was not a good fit, as we don't wan't to change
database queries depending on the users interface locale selection.

Refactoring this should fix issue #63, since the model no defines
methods at runtime.
adds migration to replace globalize tables
adds unit test for notification
adds dynamic association for notifications

Notifications are implemented aas dynamic associations,
defaults texts are fetched via ajax.
Merge pull request #80 from frab/nested_attribute_notification

Nested attribute notification