update travis and appveyor to run pytest (hopefully)

.appveyor.yml

@@ -1,9 +1,9 @@
 version: 0.3.4.{build}
 os: Windows Server 2012 R2
 install:
-- C:\Python35\Scripts\pip install ply pyreadline nose pygments prompt_toolkit
+- C:\Python35\Scripts\pip install ply pyreadline pytest pygments prompt_toolkit
 build_script:
 - C:\Python35\python setup.py install
 test_script:
-- C:\Python35\Scripts\nosetests -q
+- C:\Python35\Scripts\py.test
 

.travis.yml

@@ -6,6 +6,6 @@ python:
 install:
   - pip install -r requirements-tests.txt
 script:
-  - nosetests -q --with-coverage --cover-package=xonsh
+  - coverage run --source xonsh -m py.test
 after_success:
   - codecov

requirements-tests.txt

@@ -1,5 +1,5 @@
 ply
-nose
+pytest
 prompt-toolkit
 pygments
 coverage