replace CI tools with tox invocation

tox.ini

@@ -0,0 +1,51 @@
+# tox (https://tox.readthedocs.io/) is a tool for running tests
+# in multiple virtualenvs. This configuration file will run the
+# test suite on all supported python versions. To use it, "pip install tox"
+# and then run "tox" from this directory.
+
+[tox]
+envlist = py37,artifacts
+
+[testenv]
+# build a wheel and test it
+wheel = true
+wheel_build_env = build
+
+deps =
+    flake8
+    pytest
+    pytest-cov
+commands =
+    flake8
+    python -m pytest
+
+# whitelist commands we need
+whitelist_externals = ln
+
+[testenv:build]
+# require setuptools when building
+deps = setuptools
+
+[testenv:artifacts]
+deps =
+skip_install = true
+commands =
+    ln -sf {distdir} dist
+
+[flake8]
+max-line-length = 120
+exclude = .tox/,versioneer.py,_version.py
+max-complexity = 5
+
+[pytest]
+python_files = tests.py test_*.py
+addopts = --cov --cov-report=term --cov-report=term-missing
+
+[coverage:run]
+branch = True
+omit =
+    .tox/*
+    setup.py
+    tests/*
+    versioneer.py
+    incorporealcms/_version.py