Merge branch 'model_redesigns' into master

Merged branch model_redesigns into master. For the conflict files (bety/app/views/priors/show.html.erb and bety/app/views/priors/_index_table.html.erb) , I simply used the file from model_redesigns, since they are quite different. 
And for the file Gemfile.lock, I added what it had on model_redesigns, and I used the newer version for all dependencies. 
Don't know I am doing it correctly though.