Major api refactor.
Improved docstring on core.hash ns functions.
Remove redundant type conversion on core.sing hamc function.
Minor test reorganization.
Add implementation for bytes[] on SecretKey protocol.
Imroved core tests.
Updated doc.
Improved session example.
Rename token backend to signed token backend and add simple token backend.
Add tests for simple token backend.
Move example configs into lein profiles

Instead of having separate nested lein projects for each of the
examples, it's possible to combine the settings for each example under
different profiles in the main project. This way, you can run an example
directly from the project root with `lein with-profile sessionexample
run`.
Merge pull request #5 from jballanc/combine-project-files

Move example configs into lein profiles
Add "restrict" decorator for url independent access rules.
Update CHANGES.txt file with last implementation changes.
Add documentation of how run examples.
Documentation improvements.
Add RSASSA-PKCS1-V1_5 and ECDSA signature algorithms and split HMAC to separate ns.
Updated changelog with last added features.
Rename SecretKey protocol to ISecretKey
Rename sign test.