Use coverage instead of pytest-cov in tox (#210)

Author: chrisrink10

tox.ini

@@ -9,18 +9,19 @@ commands =
 [testenv:coverage]
 deps =
     coveralls
-    pytest
-    pytest-cov
+    coverage
 setenv   =
     COVERALLS_REPO_TOKEN = {env:COVERALLS_REPO_TOKEN}
+usedevelop = true
 commands =
-    pytest --disable-warnings --cov={envsitepackagesdir}/basilisp --cov-report html
+    coverage run --source=src/basilisp -m pytest --disable-warnings
+    coverage report
     coveralls
 
 [testenv:mypy]
 deps = mypy
 skip_install = true
-commands = 
+commands =
     mypy --ignore-missing-imports --follow-imports=skip src/basilisp
 
 [testenv:lint]