Minor stylistic changes

This is basically merging in echonest#28 but without all of
the whitespace changes.

(which my editor also kept trying to make for me!)

Author: ianp

examples/try_new_things.py

@@ -59,10 +59,9 @@ def end(self):
     def elem(self, name, value, attrs={ }):
         # delete attributes with an unset value
         for (k, v) in attrs.items():
-            if v is None or v == '':
+            if not v:
                 del attrs[k]
-        
-        if value is None or value == '':
+        if not value:
             if len(attrs) == 0:
                 return
             self._out.write(self._getIndention())

pyechonest/util.py

@@ -300,6 +300,6 @@ def fix(x):
 
 
 def map_idspace(input_idspace):
-    if input_idspace == 'spotify-WW' or input_idspace == 'spotifyv2-ZZ':
+    if input_idspace in ['spotify-WW', 'spotifyv2-ZZ']:
         return 'spotify'
     return input_idspace