usability of gamification

Challenge
- [x] 'Reward as soon as every goal is reached' box checked by default
- [x] Clicking on a challenge kanban should open challenge view, not goal list
- [x] list of users readonly
- [x] start button on challenge

Badge
- [x] When creates a challenge from badge view, set by default badge to 'For Every Succeding User' field
- [x] List of badge on employee form not the first tab

Goals
- [x] better filter than "current"

Base
- [x] add field on `ir.model` to get inherited models and be able to retrieve the field list of inherits models as well
The issue using the kind of statement is that all entries in the dictionary will share the same list. For example:
ids = [2, 3, 4]
res = dict.fromkeys(ids, [])
res[2].append('test')
print res -> all entries share the same list with the 'test' item added in them.