[core] restructure to allow PIP packaging

OK - so I have to admit I *hate* the fact that PIP seems to require a
subdirectory named like the library.

But since the PIP package is something really nifty to have (thanks to
@tony again!!!), I updated the codebase to hopefully conform with what
PIP expects. Testruns so far look promising...

bumblebee_status/core/event.py

@@ -0,0 +1,29 @@
+__callbacks = {}
+
+
+def register(event, callback, *args, **kwargs):
+    cb = callback
+    if len(args) + len(kwargs) > 0:
+        cb = lambda: callback(*args, **kwargs)
+
+    __callbacks.setdefault(event, []).append(cb)
+
+
+def clear():
+    __callbacks.clear()
+
+
+def trigger(event, *args, **kwargs):
+    cb = __callbacks.get(event, [])
+    if len(cb) == 0:
+        return False
+
+    for callback in cb:
+        if len(args) + len(kwargs) == 0:
+            callback()
+        else:
+            callback(*args, **kwargs)
+    return True
+
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4