Refactor Redis and Resque configuration to work with Unicorn

* Add redis initializer
 * Parse redis worker environment variable
 * Login to redis
 * Set redis connection to a constant
* Update resque initializer to redis connection constant
* Update example application yaml to have correct redis worker dsn
* Move resque QUEUE and VVERBOSE to Procfile to be explicit
* Update unicorn config to connect to redis using redis constant
* Remove dependent: :destroy from user, profile and gists
 * We are not deleting any of those resources
Sort profile usernames so typeahead is alphabetized
Add Redis service and environment variable to Travis CI configuration