New commit message:

Forgot to add to last commit:

The "observer" design pattern has been at least temporarily abandoned.
It's not necessary since changes can cascade from left to right through
the tabs (company tab --> contact tab --> project tab --> session tab)
so each tab just needs to update the correct tab at the correct time.
Merge branch 'master' of https://github.com/CJOlsen/payable_hours
** trying to fix a bad commit message **