Article organization

Adds show action/view for Articles and pagination. Since I couldn't find anything about pagination without using gems online (which seemed to contradict the nature of this project), I took inspiration from how @pk-nb pulled it off. Resolves #9 
That's a rule that I generally try to stick to as well. Since I haven't done much programming with any languages that include something like `unless`, I've been giving it a shot when I can. I didn't even notice until your comment that I can get away with nothing negative here by just switching the code under the else with the code under the main conditional.