Fix travis

Also move doc requirements to requires dir

.travis.yml

@@ -1,14 +1,10 @@
 sudo: false
 language: python
+dist: xenial
 python:
-- 2.7
-- pypy
-- 3.4
-- 3.5
-- 3.6
-- 3.7-dev
+- 3.7
 install:
-- pip install -r requires/testing.txt -r docs/requirements.txt
+- pip install -r requires/development.txt
 script:
 - nosetests
 after_success:
@@ -21,6 +17,6 @@ deploy:
   password:
     secure: "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"
   on:
-    python: 3.5
+    python: 3.7
     tags: true
     repo: sprockets/sprockets.mixins.http

requires/development.txt

@@ -0,0 +1,3 @@
+-e .
+-r docs.txt
+-r testing.txt