Refactor test methods for future additions
Send a Last-Modified header
Add failing test for embedded 304 responses

i want a status code of "Not Modified" returned on subsequent requests
for a resource, but that isn't happening.
Fix up test helper methods
Use our own `EmbeddedFileResponse` class

This copies over the `EmbeddedFileResponse` class from the Nancy
project. From here, we can modify the responses to deal properly with
caching.
Add our own response class to support 304s

This code is mostly Straight Out Of Nancy (SOON?) with some embedded
flavoring.
Adjust test names
Rename Embedded file response class

i don't want to confuse my class with the default Nancy class used for
embedded file responses.
Add xml docs
No need for namespace
Merge pull request #1 from jugglingnutcase/improve-caching

Improve caching