Switch to Pipenv for dependency management

Pipfile

@@ -0,0 +1,21 @@
+[[source]]
+url = "https://pypi.org/simple"
+verify_ssl = true
+name = "pypi"
+
+[packages]
+pluggy = "*"
+selenium = "*"
+splinter = "*"
+"zope.component" = "*"
+"zope.interface" = "*"
+
+[dev-packages]
+coveralls = "*"
+flake8 = "*"
+flake8-isort = "*"
+mock = "*"
+pytest = "*"
+pytest-cov = "*"
+sphinx = "*"
+sphinx-rtd-theme = "*"

requirements/pipenv.txt

@@ -0,0 +1 @@
+pipenv==2018.7.1

tox.ini

@@ -1,21 +1,23 @@
-# Tox (http://tox.testrun.org/) 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 = py{27,36,py,py3}, docs
 
 [testenv]
+skip_install = true
 passenv = TRAVIS TRAVIS_JOB_ID TRAVIS_BRANCH
-deps = -rrequirements/tests.txt
-commands = pytest --cov {posargs}
+setenv = PIPENV_IGNORE_VIRTUALENVS=1
+deps = -rrequirements/pipenv.txt
+commands =
+    pipenv install --dev
+    pipenv run pytest --cov {posargs}
+    - pipenv run coveralls
 
 [testenv:flake8]
-deps = -rrequirements/flake8.txt
-commands = flake8 .
+commands =
+    pipenv install --dev
+    pipenv run flake8 {posargs}
 
 [testenv:docs]
 changedir = docs
-deps = -rrequirements/docs.txt
-commands = sphinx-build -W -b html -d {envtmpdir}/doctrees . {envtmpdir}/html
+commands =
+    pipenv install --dev
+    pipenv run sphinx-build -W -b html -d {envtmpdir}/doctrees . {envtmpdir}/html