Use standard cover setup

Replace coverage testing with the normal way coverage is tested in
OpenStack.

Change-Id: Ic171e33a876029727b473481e56fdd94fce5ec6e

.coveragerc

@@ -1,9 +1,11 @@
 [run]
 branch = True
+source = jenkins
 omit =
     .tox*
 
 [report]
+ignore_errors = True
 exclude_lines =
     pragma: no cover
     raise NotImplementedError

.gitignore

@@ -13,3 +13,7 @@
 /.coverage
 /coverage*.xml
 /junit*.xml
+
+# Unit test / coverage reports
+cover/
+

tox.ini

@@ -11,10 +11,7 @@ deps = -r{toxinidir}/test-requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:cover]
-commands =
+commands = python setup.py test --coverage --testr-args='{posargs}'
-    coverage run -m discover
-    coverage report --omit="tests/*" --show-missing
-    coverage html --omit="tests/*" -d cover
 
 [testenv:pep8]
 commands = flake8