Fix TravisCI build
Fix TravisCI build

Ruby 2.3 and Rails 4.2 build failed because of incorrect bundler version
in TravisCI. Bypass this one by deleting default bundler present in
TravisCI.

outstand/doorkeeper,mavenlink/doorkeeper,outstand/doorkeeper,doorkeeper-gem/doorkeeper,jasl/doorkeeper,jasl/doorkeeper,mavenlink/doorkeeper,mavenlink/doorkeeper,doorkeeper-gem/doorkeeper,outstand/doorkeeper,jasl/doorkeeper,doorkeeper-gem/doorkeeper