Auto merge of #2412 - micbou:appveyor-coverage, r=Valloric

[READY] Enable coverage on AppVeyor

I forgot to do that when adding coverage.

Also, the `cover` folder is created at the project root, not in the `python` folder.

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.gitignore

@@ -28,7 +28,7 @@ pip-log.txt
 
 # Unit test / coverage reports
 .coverage
-python/cover/
+cover/
 .tox
 nosetests.xml
 .noseids

appveyor.yml

@@ -1,5 +1,6 @@
 version: '{build}'
 environment:
+  COVERAGE: true
   matrix:
   - arch: 32
     python: 35