Update to Twitter api v1.1 for grabbing user-data

I tried to set-up brug locally and encountered a Bad Authentication Data-error (215) when running db/seeds.rb. 

Seems the code to grab data from a specific user still uses the old Twitter API v1, which has been retired. The new v1.1 requires authentication for everything. 

I've also created a new class which contains the config for the Twitter-gem. I didn't want to put the same config-lines in 2 methods and making it into a class-method would add it to the public interface of Member (as class methods can't be made private).