CONTRIBUTING: Fix location of language images
Merge pull request #947 from sit/doc-fix

CONTRIBUTING: Fix location of language images
java: Start track with Bob

This is the complete skeleton for enabling Java, from curriculum
through the first exercise. Java is listed in the main curriculum.rb
but commented out; we will activate once there are a sufficient body
of exercises ported.

The java.png icon is taken from http://findicons.com/icon/88943/java?id=89126,
released under a freeware license.

Describe how to minimally set-up Java and JUnit. (Future work may
try to see if we can get Locale.additional_files working and provide
build integration via Gradle or Maven.)

The BobTest is a straight up port of the Python Bob.

This starts the path of fixing #933.
Merge pull request #946 from sit/java

java: Start track with Bob
Remove mongoid -- the gem is now superfluous
Do not require database cleaner by default
Upgrade faraday
Upgrade pg
Upgrade newrelic
Upgrade pony
Delete associated records on unsubmit. Fixes #948.

Notifications, comments, views, likes, mutes are all irrelevant if the
submission goes away.
Upgrade puma
Update rack-flash
Update redcarpet
Upgrade sinatra
Update database_cleaner
Upgrade minitest
Upgrade will_paginate-bootstrap
Upgrade activerecord... a little bit.

activerecord 4.0.1 requires minitest 4.x, and all of the exercism tests
are minitest 5.x. I can't win. Either activerecord is up-to-date, or
minitest is. No matter what, my gem dependencies will be reported as
outdated.

I suppose the bottom line is that I care more about minitest than
activerecord, so activerecord can go languish in its miserable
outdatedness.
Delete spurious equality definition on User.