Style changes to README
Instructions for contributing to project
Update name of gemspec in Gemfile
Ignore .swp and .sqlite3-journal files
Fix Cucumber tests

* Add User.to_s method to render impersonation header correctly
* Add config/initializers/user_impersonate.rb to test application to fix redirects
* Run Minitest and Cucumber tests in Travis-CI
* Update README to describe how to run all tests