Drop inject and add TorqueBox.fetch (TORQUE-1054, TORQUE-1056)

Convert all internal uses of fetch to TorqueBox.fetch and modify most
integration tests to use TorqueBox.fetch, leaving a couple using the old
'include TorqueBox::Injectors' to ensure backwards compatibility.

Since TorqueSpec still uses inject, we've retained a tiny stub in injectors.rb
of TorqueSpec::Daemon#inject that just calls TorqueBox.fetch.