Initial refactoring of backend specific contexts.
Don't forget to provide an interface.
Rename _OneTimeCipherContext
Merge pull request #178 from dreid/composable-contexts

[WIP] Reduce the backend's API surface by making it a vendor of implementation specific CipherContext providers.
Merge pull request #179 from reaperhulk/gcm-vectors

AES GCM vectors from NIST
add some error parsing macros
Also linkcheck the docs
Update the requirements file for our direct invocations of coverage
Merge pull request #185 from alex/linkcheck

Also linkcheck the docs
Merge pull request #186 from alex/reqs

Update the requirements file for our direct invocations of coverage
Merge pull request #181 from reaperhulk/error-handling

Add some error parsing macros
Move primtives into a hazmat package
Move the bindings into the hazmat module
Put recipes first
Warn about dragons and dinosaurs with laser guns
Move the module name to it's own variable
Move the danger to the very top of the file
Handle the deeper package directory
Hazard -> Hazardous
Merge pull request #188 from dstufft/hazmat

Create a Hazardous Materials Area