fix 311 by adding <title>s

add an application helper file for dynamically changing title with a default
define titles for submissions and exercises
add tests for default and defined title
Fix different duplicates test
Add CodeClimate's badge to README.

[ci skip]
rna: Ditch first example.
rna: Extend example.

Forward ==, to_str, to_s.
Extract NucleicAcid baseclass.
Add RibonucleicAcid class.
rna: Extend tests. Use long classnames.
adjustments for changes that fix 311

more specific helper name
titles now have slugs, language, and user
Refactor ruby:word-count
A little less confrontation

Changing the word "arguments" to "discussion threads" on the dashboard.
(It's presented to the students as conversation, not conflict.)
Top level navigation by language

This splits the server side rendering by language with links along the
top nav bar. Home now navigates to nitless submissions from all
languages.
Remove unused date routing code

Not squashing these commits so the code stays indexed. This is a lesser
act of code hoarding.
Create many seeds for realism
Show count of nits by others and revision number

This suggests changes to the data displayed on the dashboard. Now:

- Nits are counted only if they are submitted by others, so a user can
  comment on their own code without "penalty".

- The arguments/discussions count only goes up when the user
  participates in the discussion. This is a different kind of signal
  than a third user chiming in, as it shows that the user has
  (implicitly) acknowledged the feedback of the nit.

- A new number is shown reflecting the revision count of the submission.
  This helps a potential nitpicker better distinguish early code from
  code that is likely closer to the end.

Basic tests are added for each kind of data. The routines that sort
pending requests have also been adjusted to conform to this suggestion.

(I cannot figure out the best way to test the views on a local
installation. I'm sorry about that. I would be happy to work through
that if someone can help me figure out how to access a local
installation as an admin user, preferably without creating too many fake
github accounts.)

(I also do not know how this performs with MongoDB. I followed
the style of other methods and used simple selects or maps based on the
retrieved data.)
Tweak ruby:leap-year
Probably best not to show inheriting from core classes.
Note about using `.ruby-version` should you wish
Improve setup instructions for development
Update bob_test.rb

This clear the screen, regardless of its height.
Update anagram_test.rb
Merge pull request #328 from sbagdat/patch-1

Fix different duplicates test