User best practices

* Use before_action instead before_filter
* Use a better way for renders
Add position catalog to user
Add skill catalog
Add testing for achivable

* Preventing possible refactorization here
Add model testing for position catalog

* Validate name of position
Add skill testing situation
Use expect instead of should
Change name instead of use a wordy helper use title
Add user model test
Should matchers implementation

* Create missing join migration
* Add shoulda-matchers gem
* Use shoulda properly
Use shoulda for missing models
Improve coverage
Remove description because testing talks by himself
Merge pull request #12 from crowdint/feature_modeling_database

Feature modeling database