Build bug with Python 3.2

[guest]

The build fails with an error due to the fact that .keys() is an iterator in Python 3 and not a list. Wrapping it with list() solves the issue in Python 2 and 3.

[guest]

Broken file attachment feature is broken. Patch:

Index: elixir/options.py
===================================================================
--- elixir/options.py	(revision 534)
+++ elixir/options.py	(working copy)
@@ -230,7 +230,7 @@
     table_options={}
 )
 
-valid_options = options_defaults.keys() + [
+valid_options = list(options_defaults.keys()) + [
     'metadata',
     'session',
     'collection'