Make middleware dependencies explicit

clj-cas-client depends on both the params and session middlewares. The
params middleware is idempotent, so there's no harm in adding it
ourselves. The session middleware must only be added once, so document
the dependency in README.
Merge pull request #2 from noidi/explicit-middleware-dependencies

Make middleware dependencies explicit
Use :query-params instead of :params

Fixes clj-cas-client breaking when used with the common
wrap-keyword-params middleware. Also ensures that only query parameters
are watched for a parameter called "ticket" (the :params map may also
contain data from a form submission or a JSON body).
Merge pull request #3 from noidi/query-params

Use :query-params instead of :params
Update the assertion and ticket collection to handle either keyword or string parameter names