.appveyor.yml: drop py34; run coverage and upload to codecov

We no longer run tests on python3.4 on Windows; 2.7 and 3.5 are enough for Windows I believe.
We do test python3.4 on Linux (not for long, I hope).

We shall add 3.6 when Appveyor provides that by default.

.appveyor.yml

@@ -2,32 +2,22 @@ environment:
   matrix:
     - JOB: "2.7.12 32-bit"
       PYTHON_HOME: "C:\\Python27"
-      TOXENV: "py27"
+      TOXENV: "py27-cov"
       TOXPYTHON: "C:\\Python27\\python.exe"
 
-    - JOB: "3.4.4 32-bit"
-      PYTHON_HOME: "C:\\Python34"
-      TOXENV: "py34"
-      TOXPYTHON: "C:\\Python34\\python.exe"
-
     - JOB: "3.5.2 32-bit"
       PYTHON_HOME: "C:\\Python35"
-      TOXENV: "py35"
+      TOXENV: "py35-cov"
       TOXPYTHON: "C:\\Python35\\python.exe"
 
     - JOB: "2.7.12 64-bit"
       PYTHON_HOME: "C:\\Python27-x64"
-      TOXENV: "py27"
+      TOXENV: "py27-cov"
       TOXPYTHON: "C:\\Python27-x64\\python.exe"
 
-    - JOB: "3.4.4 64-bit"
-      PYTHON_HOME: "C:\\Python34-x64"
-      TOXENV: "py34"
-      TOXPYTHON: "C:\\Python34-x64\\python.exe"
-
     - JOB: "3.5.2 64-bit"
       PYTHON_HOME: "C:\\Python35-x64"
-      TOXENV: "py35"
+      TOXENV: "py35-cov"
       TOXPYTHON: "C:\\Python35-x64\\python.exe"
 
 install:
@@ -50,10 +40,9 @@ install:
 
   # upgrade pip and setuptools to avoid out-of-date warnings
   - "python -m pip install --disable-pip-version-check --user --upgrade pip setuptools"
-  - "python -m pip --version"
 
   # install the dependencies to run the tests
-  - "python -m pip install -r dev-requirements.txt"
+  - "python -m pip install tox"
  
 
 build: false
@@ -61,6 +50,9 @@ build: false
 test_script:
   - "tox"
 
+after_test:
+  - "tox -e codecov"
+
 notifications:
   - provider: Email
     to: