reduce number of tox and travis envs

bump minimum werkzeug version to fix tests
cache pip pacakges on travis
collect branch coverage
collect coverage of test code
report coverage across envs
test building docs
enable codecov integration

.travis.yml

@@ -1,52 +1,61 @@
 sudo: false
 language: python
 
-python:
-  - "2.6"
-  - "2.7"
-  - "pypy"
-  - "3.3"
-  - "3.4"
-  - "3.5"
-  - "3.6"
-
-env:
-  - REQUIREMENTS=lowest
-  - REQUIREMENTS=lowest-simplejson
-  - REQUIREMENTS=release
-  - REQUIREMENTS=release-simplejson
-  - REQUIREMENTS=devel
-  - REQUIREMENTS=devel-simplejson
-
 matrix:
-  exclude:
-    # Python 3 support currently does not work with lowest requirements
-    - python: "3.3"
-      env: REQUIREMENTS=lowest
-    - python: "3.3"
-      env: REQUIREMENTS=lowest-simplejson
-    - python: "3.4"
-      env: REQUIREMENTS=lowest
-    - python: "3.4"
-      env: REQUIREMENTS=lowest-simplejson
-    - python: "3.5"
-      env: REQUIREMENTS=lowest
-    - python: "3.5"
-      env: REQUIREMENTS=lowest-simplejson
-    - python: "3.6"
-      env: REQUIREMENTS=lowest
-    - python: "3.6"
-      env: REQUIREMENTS=lowest-simplejson
+  include:
+    - python: 3.6
+      env: TOXENV=py-release,codecov
+    - python: 3.5
+      env: TOXENV=py-release,codecov
+    - python: 3.4
+      env: TOXENV=py-release,codecov
+    - python: 3.3
+      env: TOXENV=py-release,codecov
+    - python: 2.7
+      env: TOXENV=py-release,codecov
+    - python: 2.6
+      env: TOXENV=py-release,codecov
+    - python: pypy
+      env: TOXENV=py-release,codecov
+    - python: nightly
+      env: TOXENV=py-release
+    - python: 3.6
+      env: TOXENV=docs-html
+    - python: 3.6
+      env: TOXENV=py-release-simplejson,codecov
+    - python: 2.7
+      env: TOXENV=py-release-simplejson,codecov
+    - python: pypy
+      env: TOXENV=py-release-simplejson,codecov
+    - python: 3.6
+      env: TOXENV=py-devel,codecov
+    - python: 3.3
+      env: TOXENV=py-devel,codecov
+    - python: 2.7
+      env: TOXENV=py-devel,codecov
+    - python: 2.6
+      env: TOXENV=py-devel,codecov
+    - python: pypy
+      env: TOXENV=py-devel,codecov
+    - python: 3.6
+      env: TOXENV=py-lowest,codecov
+    - python: 3.3
+      env: TOXENV=py-lowest,codecov
+    - python: 2.7
+      env: TOXENV=py-lowest,codecov
+    - python: 2.6
+      env: TOXENV=py-lowest,codecov
+    - python: pypy
+      env: TOXENV=py-lowest,codecov
 
 install:
-    - pip install tox
+  - pip install tox
 
 script:
-    - tox -e py-$REQUIREMENTS
+  - tox
 
-branches:
-  except:
-    - website
+cache:
+  - pip
 
 notifications:
   email: false