[modules] Add first "real" module: kernel

Since 'kernel' is small and shows static information, have this be the
very first module added.

modules/kernel.py

@@ -0,0 +1,14 @@
+# pylint: disable=C0111,R0903
+
+"""Shows Linux kernel version information"""
+
+import platform
+
+import core.module
+import core.widget
+
+class Module(core.module.Module):
+    def __init__(self):
+        super().__init__(core.widget.Widget(platform.release()))
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

tests/modules/test_kernel.py

@@ -0,0 +1,16 @@
+import unittest
+
+import modules.kernel
+
+class kernel(unittest.TestCase):
+    def setUp(self):
+        self.someKernel = 'this-is-my-kernel'
+        with unittest.mock.patch('modules.kernel.platform') as platform:
+            platform.release.return_value = self.someKernel
+            self.module = modules.kernel.Module()
+
+    def test_full_text(self):
+        self.assertEqual(1, len(self.module.widgets()))
+        self.assertEqual(self.someKernel, self.module.widgets()[0].full_text())
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4