Resolves gh-244 option to disable global define.amd

Config option and tests added to disable the global define.amd
This change and tests enables a user to mix script tags with their
loader, with an interface to enable/disable the primary form of
detection: define.amd.

This addresses use cases where a user has loaded Inject, and then
places a script tag on the page that tests for define&&define.amd,
attempting to register an anonymous module.

gh-244