[core/theme] Add prefix/postfix methods

Add a way to specify prefix and postfix strings to the full text of a
widget's text. Currently, the theme does not fill those yet.

see #23

bumblebee/config.py

@@ -7,12 +7,14 @@ module parameters, etc.) to all other components
 import argparse
 
 MODULE_HELP = ""
+THEME_HELP = ""
 
 def create_parser():
     """Create the argument parser"""
     parser = argparse.ArgumentParser(description="display system data in the i3bar")
     parser.add_argument("-m", "--modules", nargs="+", default=[],
-                        help=MODULE_HELP)
+        help=MODULE_HELP)
+    parser.add_argument("-t", "--theme", default="default", help=THEME_HELP)
     return parser
 
 class Config(object):
@@ -32,4 +34,8 @@ class Config(object):
             "name": x if not ":" in x else x.split(":")[1],
         } for x in self._args.modules]
 
+    def theme(self):
+        """Return the name of the selected theme"""
+        return self._args.theme
+
 # vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4