Several fixes

* Refactored BaseModel for efficiency
* Added plugin metaclass to keep track of plugin types
* Moved plugins to examples dir (in a previous commit)
* Simplified validation in parse_params
* Added convenience methods to mock requests in tests
* Changed help schema to use `.valid_parameters` instead of `.parameters`,
which was used in results to show parameters provided by the user.
* Improved UI
    * Added basic parameters
    * Fixed bugs in parameter handling
    * Refactored and cleaned code

tests/test_blueprints.py

@@ -162,5 +162,5 @@ class BlueprintsTest(TestCase):
         resp = self.client.get("/api/?help=true")
         self.assertCode(resp, 200)
         js = parse_resp(resp)
-        assert "parameters" in js
-        assert "help" in js["parameters"]
+        assert "valid_parameters" in js
+        assert "help" in js["valid_parameters"]