Revert "Make bundler output verbose to debug issue on Travis CI."
Revert "Make bundler output verbose to debug issue on Travis CI."

This reverts commit c8bc6d20ddc0e894175632615a131b9d5077ec50.

I came up with a workaround for the fatal Bundler error on Travis Ci
in Ruby 1.8.7 in [1], so this debug output is no longer needed.

[1] 66bab2a8f4e7cd8734bf88e6f32157c0d5153125

10io/mocha