remove version numbers from requirements.txt

.travis.yml

@@ -1,7 +1,7 @@
 language: python
 python:
-- "3.2"
+- 3.2
-- "3.3"
+- 3.3
 install:
-- "pip install -r requirements.txt --use-mirrors"
+- pip install -r requirements.txt --use-mirrors
 script: nosetests

requirements.txt

@@ -1,5 +1,4 @@
-lxml==3.2.1
+lxml
-mock==1.0.1
+mock
-nose==1.3.0
+nose
-requests==1.2.3
+requests
-urllib3==1.6