Test loader CSP compliance

[eheasley]

Task

Write tests that confirm the loader's compliance with the browser's content security policy (CSP).

Loader Functional Testing Pattern

Write loader tests as functional tests to provide a clean environment in which the loader can operate. Whenever possible use the pattern outlined in [this wiki](../wiki/Loader Functional Testing Pattern) for inspecting test results.

[msssk]

I added CSP tests:
master...msssk:csp-tests

Ed, should I PR this branch, or hang onto it until we can add dojo-core as a normal devDependency (right now it's an npm linked package.

[msssk]

It occurs to me that since the CSP tests now have their own HTTP server, we should probably configure the server to send CSP headers (right now CSP is being enabled in the test pages using a meta tag).

Edit: done in 4c344c4b

[rorticus]

CSP tests from #104 merged.