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

example-plugins/dummy_plugin/dummy.py

@@ -0,0 +1,11 @@
+from senpy.plugins import SentimentPlugin
+
+
+class DummyPlugin(SentimentPlugin):
+    def analyse_entry(self, entry, params):
+        entry['nif:isString'] = entry['nif:isString'][::-1]
+        entry.reversed = entry.get('reversed', 0) + 1
+        yield entry
+
+    def test(self):
+        pass

example-plugins/dummy_plugin/dummy.senpy

@@ -0,0 +1,15 @@
+{
+    "name": "Dummy",
+    "module": "dummy",
+    "description": "I am dummy",
+    "author": "@balkian",
+    "version": "0.1",
+    "extra_params": {
+        "example": {
+            "@id": "example_parameter",
+            "aliases": ["example", "ex"],
+            "required": false,
+            "default": 0
+        }
+    }
+}

example-plugins/dummy_plugin/dummy_noinfo.py

@@ -0,0 +1,27 @@
+from senpy.plugins import SentimentPlugin
+
+
+class DummyPlugin(SentimentPlugin):
+
+    description = 'This is a dummy self-contained plugin'
+    author = '@balkian'
+    version = '0.1'
+
+    def analyse_entry(self, entry, params):
+        entry['nif:isString'] = entry['nif:isString'][::-1]
+        entry.reversed = entry.get('reversed', 0) + 1
+        yield entry
+
+    test_cases = [{
+        "entry": {
+            "nif:isString": "Hello world!"
+        },
+        "expected": [{
+            "nif:isString": "!dlrow olleH"
+        }]
+    }]
+
+
+if __name__ == '__main__':
+    d = DummyPlugin()
+    d.test()

example-plugins/dummy_plugin/dummy_noinfo.senpy

@@ -0,0 +1,2 @@
+name: DummyNoInfo
+module: dummy_noinfo

example-plugins/dummy_plugin/dummy_required.senpy

@@ -0,0 +1,14 @@
+{
+    "name": "DummyRequired",
+    "module": "dummy",
+    "description": "I am dummy",
+    "author": "@balkian",
+    "version": "0.1",
+    "extra_params": {
+        "example": {
+            "@id": "example_parameter",
+            "aliases": ["example", "ex"],
+            "required": true
+        }
+    }
+}