Stop testing against pypy

Same as c24d7f1

marshmallow is pure python. As long as tests pass on 2.7, they
should pass on pypy, too. Testing against pypy isn't worth
the added Travis build time.

.travis.yml

@@ -15,7 +15,6 @@ jobs:
   - { python: '3.4', env: TOXENV=py34 }
   - { python: '3.5', env: TOXENV=py35 }
   - { python: '3.6', env: TOXENV=py36 }
-  - { python: 'pypy', env: TOXENV=pypy }
   - { python: '3.6', env: TOXENV=docs }
 
   - stage: PyPI Release

CONTRIBUTING.rst

@@ -110,7 +110,7 @@ To run syntax checks: ::
 
     $ tox -e lint
 
-(Optional) To run tests on Python 2.6, 2.7, 3.4, 3.5, and PyPy virtual environments (must have each interpreter installed): ::
+(Optional) To run tests on Python 2.6, 2.7, 3.4, 3.5, and 3.6 virtual environments (must have each interpreter installed): ::
 
     $ tox
 

setup.py

@@ -72,8 +72,6 @@ def read(fname):
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
-        'Programming Language :: Python :: Implementation :: CPython',
-        'Programming Language :: Python :: Implementation :: PyPy',
     ],
     test_suite='tests',
     project_urls={

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = lint,py26,py27,py34,py35,pypy,docs
+envlist = lint,py26,py27,py34,py35,docs
 
 [testenv]
 extras = tests,reco
@@ -12,9 +12,6 @@ commands = flake8 .
 [testenv:py26]
 commands = pytest --ignore=tests/test_py3/ {posargs}
 
-[testenv:pypy]
-commands = pytest --ignore=tests/test_py3/ {posargs}
-
 [testenv:py27]
 commands = pytest --ignore=tests/test_py3/ {posargs}