Make hint comparison more intelligent

"easy foo/1 bar/2" and "easy bar/2 foo/1" are simply different ways of
writing the same hint, so the corresponding Hint objects should compare
as equal.

Signed-off-by: Adam D. Barratt <adam@adam-barratt.org.uk>

hints.py

@@ -77,7 +77,12 @@ class Hint(object):
         return self._hint
 
     def __eq__(self, other):
-        return str(self) == str(other)
+        if self.type != other.type:
+            return False
+        elif self.type == 'age-days' and self.days != other.days:
+            return False
+        else:
+            return frozenset(self.packages) == frozenset(other.packages)
 
     @property
     def type(self):