Added Druid wild shapes, tweaked armor, and fixed some bugs.

Druid's can now add ``wild_shapes = `` to their character file. "Light
leather armor" is now just "Leather Armor".

dungeonsheets/exceptions.py

@@ -9,3 +9,6 @@ class LatexError(OSError):
 
 class LatexNotFoundError(LatexError):
     """PDFLatex did not execute correctly."""    
+
+class MonsterError(AttributeError):
+    """Error retriving or using a D&D Monster."""