add nltk to requirements

- needed for chemical equation parsing, which is about to appear in capa

add nltk to requirements
66604fd0 · Victor Shnayder · 9e02b3ce · 66604fd0
Commit 66604fd0 authored 12 years ago by Victor Shnayder
--- a/requirements.txt
+++ b/requirements.txt
@@ -49,3 +49,4 @@ networkx
 pygraphviz
 -r repo-requirements.txt
 pil
+nltk