Adding new & create actions for problems controller

Limit access to guest users.
Problems now require a judge
Let authenticated users create problems

Adding a simple form to create a problem.
Adding associations between models
Adding simple categorization model

This is the join model between a problem and a category.
Adding Chosen.js library

Make select fields better.
Adding simple Category factory
Fix Categorization factory
Let users add categories to problems on create.
Link Travis-ci branch on README

[ci-skip]
Use the config/secrets file to store app secrets
Adding CarreierWave & Fog
Adding basic carrierwave config.
Adding problem partial and use real problems on views
Move the solution to a dummy solutions partial
Only render problem if there's one to render.
Make a better Carrierwave config.
Merge pull request #5 from nhocki/problems

Problems CRUD