Document that applicaiton.yml requires snakeyaml

Update documentation to reference the need for a yaml library to be on
the classpath.

Fixes gh-313
Merge pull request #313 from madorb/master

* pull313:
  Document that applicaiton.yml requires snakeyaml
Prevent 404s in README.md links

Fix links to ensure that they don't cause 404 errors when published to
Github Pages.

Fixes gh-304
Merge pull request #304 from adambro/patch-1

* patch-1:
  Prevent 404s in README.md links