[modules/caffeine] Re-implement caffeine module

Add caffeine module & add a framework for testing it (no tests yet,
though).

see #23

tests/modules/test_caffeine.py

@@ -0,0 +1,21 @@
+# pylint: disable=C0103,C0111
+
+import json
+import unittest
+import mock
+
+import bumblebee.input
+from bumblebee.input import I3BarInput
+from bumblebee.modules.caffeine import Module
+from tests.util import MockEngine, MockConfig, assertPopen
+
+class TestCaffeineModule(unittest.TestCase):
+    def setUp(self):
+        self.engine = MockEngine()
+        self.engine.input = I3BarInput()
+        self.engine.input.need_event = True
+        self.engine.input.need_valid_event = True
+        self.config = MockConfig()
+        self.module = Module(engine=self.engine, config={ "config": self.config })
+        for widget in self.module.widgets():
+            widget.link_module(self.module)