Fix string-formatting args when raising LookupError

Previously, this would trigger

 TypeError: not enough arguments for format string

1 files changed, 11 insertions, 0 deletions

diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..18af92a
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,11 @@
+[tox]
+envlist = py26, py27, py33, py34, py35, pypy
+
+[testenv]
+deps =
+    # Paste works on Python 3 since Paste 2.0
+    Paste
+    pytest
+    pytest-cov
+commands =
+    py.test {posargs}