Install psycopg2-binary

Currently Travis CI builds are failing with a message asking us to
install the binary version, so let's give that a try.

Remove Python 2.6 and Python 3.3 from the build matrix, as those
versions are not supported by the core team or Sphinx.

.travis.yml

@@ -6,9 +6,7 @@ cache: pip
 language: python
 
 python:
-  - "2.6"
   - "2.7"
-  - "3.3"
   - "3.4"
   - "3.5"
   - "3.6"
@@ -19,12 +17,6 @@ python:
 
 matrix:
   include:
-    - python: "2.6"
-      env: WITHSIMPLEJSON=false WITHFUTURE=true
-    - python: "2.6"
-      env: WITHSIMPLEJSON=true WITHFUTURE=false
-    - python: "2.6"
-      env: WITHSIMPLEJSON=true WITHFUTURE=true
     - python: "2.7"
       env: WITHFUTURE=true
 

requirements/test-cpython.txt

@@ -1,2 +1,2 @@
 -r test.txt
-psycopg2
+psycopg2-binary