Merge PR #64 -- make docs work at github

Dual docs -- issue #63

docs/index.rst

 .. currentmodule:: astor
 
+.. github display
+
+  ************************************************************************************
+  NOTE: This file was designed to be viewed at http://astor.readthedocs.io/en/latest/
+  ************************************************************************************
+
+  Some content will not display properly when viewing using the github browser.
+
+
 ============================
 astor -- AST observe/rewrite
 ============================
@@ -15,7 +24,6 @@ astor -- AST observe/rewrite
 
 astor is designed to allow easy manipulation of Python source via the AST.
 
-
 Getting Started
 ---------------
 
@@ -65,12 +73,20 @@ areas:
 Classes
 ---------
 
+.. github display
+
+  .. class:: CodeToAst
+
 .. class:: CodeToAst
 
     This is the base class for the helper function code_to_ast.
     It may be subclassed, but probably will not need to be.
 
 
+.. github display
+
+  .. class:: TreeWalk(node=None)
+
 .. class:: TreeWalk(node=None)
 
     The TreeWalk class is designed to be subclassed in order
@@ -79,6 +95,10 @@ Classes
     at present :(
 
 
+.. github display
+
+  .. class:: ExplicitNodeVisitor
+
 .. class:: ExplicitNodeVisitor
 
     The ExplicitNodeVisitor class subclasses the ast.NodeVisitor
@@ -212,7 +232,7 @@ Command line utilities
 --------------------------
 
 rtrip
-''''''
+~~~~~
 
 There is currently one command-line utility::