[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