Remove MTSR gem. Errors now include:

NoMethodError: undefined method `let' for ActiveSupport::TestCase:Class
/Users/kencollins/Repositories/mtsr_integration/test/test_helper.rb:9:in `<class:TestCase>'
/Users/kencollins/Repositories/mtsr_integration/test/test_helper.rb:5:in `<top (required)>'
/Users/kencollins/Repositories/mtsr_integration/test/helpers/users_helper_test.rb:1:in `<top (required)>'
Tasks: TOP => test:run => test:units