Use pytest instead of py.test per upstream recommendation, #dropthedot

http://blog.pytest.org/2016/whats-new-in-pytest-30/
https://twitter.com/hashtag/dropthedot

Author: scop

Diff for: Makefile

@@ -29,7 +29,7 @@ lint-roll:
 	$(MAKE) lint
 
 test:
-	py.test tests
+	pytest tests
 
 test-all:
 	tox

Diff for: README.md

@@ -162,7 +162,7 @@ Or, you can run multi-process tests in one command, but without color:
 
 ```sh
 # in the project root:
-py.test --numprocesses=4 --looponfail --maxfail=1
+pytest --numprocesses=4 --looponfail --maxfail=1
 # the same thing, succinctly:
 pytest -n 4 -f --maxfail=1
 ```

Diff for: pytest.ini

@@ -4,4 +4,4 @@ python_paths= .
 xfail_strict=true
 
 [pytest-watch]
-runner= py.test --failed-first --maxfail=1 --no-success-flaky-report
+runner= pytest --failed-first --maxfail=1 --no-success-flaky-report

Diff for: tox.ini

@@ -26,15 +26,15 @@ ignore=
 [testenv]
 usedevelop=True
 commands=
-    core: py.test {posargs:tests/core}
-    ens: py.test {posargs:tests/ens}
-    integration-goethereum-ipc: py.test {posargs:tests/integration/go_ethereum/test_goethereum_ipc.py}
-    integration-goethereum-http: py.test {posargs:tests/integration/go_ethereum/test_goethereum_http.py}
-    integration-goethereum-ws: py.test {posargs:tests/integration/go_ethereum/test_goethereum_ws.py}
-    integration-ethtester: py.test {posargs:tests/integration/test_ethereum_tester.py}
-    integration-parity-ipc: py.test -s {posargs:tests/integration/parity/test_parity_ipc.py}
-    integration-parity-http: py.test -s {posargs:tests/integration/parity/test_parity_http.py}
-    integration-parity-ws: py.test -s {posargs:tests/integration/parity/test_parity_ws.py}
+    core: pytest {posargs:tests/core}
+    ens: pytest {posargs:tests/ens}
+    integration-goethereum-ipc: pytest {posargs:tests/integration/go_ethereum/test_goethereum_ipc.py}
+    integration-goethereum-http: pytest {posargs:tests/integration/go_ethereum/test_goethereum_http.py}
+    integration-goethereum-ws: pytest {posargs:tests/integration/go_ethereum/test_goethereum_ws.py}
+    integration-ethtester: pytest {posargs:tests/integration/test_ethereum_tester.py}
+    integration-parity-ipc: pytest -s {posargs:tests/integration/parity/test_parity_ipc.py}
+    integration-parity-http: pytest -s {posargs:tests/integration/parity/test_parity_http.py}
+    integration-parity-ws: pytest -s {posargs:tests/integration/parity/test_parity_ws.py}
     doctest: make -C {toxinidir}/docs doctest
 deps =
     -r{toxinidir}/requirements-dev.txt