removed unused column number from pagers
refactored Pager#numbers and Pager#groups
The Pager now also lists Numbers from the Users in the Pager's Group.

Fixes #5.
Also cleaned up some unused Routes and Actions.
Pager pikett groups are now correctly validated for uniqueness.

fixes #4.
Fixed Pager.having_number. Also: cleanup.
Merge pull request #7 from mhutter/refactor_pager

Refactored Pager