Don't think we need to explicitly list out each build setup anymore, …

…since we can just use the standard matrix behavior.

.travis.yml

@@ -1,25 +1,15 @@
 language: python
 sudo: false
 
-matrix:
-  include:
-    - python: 2.7
-      env: NB_VERSION=4
-    - python: 2.7
-      env: NB_VERSION=5
-
-    - python: 3.4
-      env: NB_VERSION=4
-    - python: 3.4
-      env: NB_VERSION=5
-
-    - python: 3.6
-      env: NB_VERSION=4
-    - python: 3.6
-      env: NB_VERSION=5
-
-    - env: FLAKE8=true NB_VERSION=5
-    - env: NOTEST=true NB_VERSION=5
+python:
+  - "2.7"
+  - "3.4"
+  - "3.6"
+env:
+  - NB_VERSION=4
+  - NB_VERSION=5
+  - FLAKE8=true
+  - NOTEST=true
 
 addons:
   postgresql: "9.3"