[themes] Do not automatically download symbols.json

In order to use symbol files, symbol.json needs to be created manually
now.

Also, remove symbol usage from the prepackaged themes to avoid
breakage.

fixes #216

bumblebee/theme.py

@@ -61,10 +61,7 @@ class Theme(object):
         except Exception:
             pass
         try:
-            if not os.path.exists("{}/symbols.json".format(path)):
-                data = yaml.load(requests.get("https://raw.githubusercontent.com/FortAwesome/Font-Awesome/master/src/icons.yml").text)
-                with io.open("{}/symbols.json".format(path), "w") as f:
-                    json.dump(data, f)
+            if os.path.exists("{}/symbols.json".format(path)):
                 data = json.load(io.open("{}/symbols.json".format(path)))
                 self._symbols = {}
                 for icon in data["icons"]:

themes/icons/awesome-fonts.json

@@ -3,8 +3,8 @@
 		"separator": "", "padding": " ",
 		"unknown": { "prefix": "" }
 	},
-	"date": { "prefix": "${calendar}" },
-	"time": { "prefix": "${clock-o}" },
+	"date": { "prefix": ""	},
+	"time": { "prefix": "" },
 	"datetime": { "prefix": "" },
 	"memory": { "prefix": "" },
 	"cpu": { "prefix": "" },