Corrected several of the models methods

1.) Created in a new method in 'auction' that returns the last bid of the auction
  - This is then used when a participant is submitting a bid to ensure the bid is higher. It is also used for when an auctioneer is closing an auction to see whether the auction was a success or not.

2.) Removed some unnecessary arguments in methods and replaced them with 'self'.
Cleaned up call_item method in the Item Model
Noticed my test suite was running with 0 failures for the first run, and then getting various errors with each additional run.

Found this was due to the uniqueness validation on several attributes and the Faker gem was not in fact making completly unique names each run.

Added the gem 'database-cleaner' to clear out the test database before each run of the test suite to ensure there are no duplicate records.
Commented out config.formatter = :documentation because it was causing the rspec results to display twice
When an auctioneer calls an auction, item's status changes to sold, no more bids can go through
Added a query_item method to Participant and Auctioneer model

This method takes in an item name and checks the status of that item
If the item is sold it will return who it was sold to and the price it sold
for, otherwise it will return all the bids associated with that item.
Merge pull request #7 from Onaracs/task/test_model_methods

Task/update model methods