Fix coverage option and execution

--coverage-package-name option was no longer supported by 'testr'[1].
This commit replaces from 'testr' to 'test' as coverage option.

[1] https://review.openstack.org/#/c/217847/

Change-Id: Iedb3ae3171733e129de6180094022df2c8b85ea3

.gitignore

@@ -47,3 +47,7 @@ etc/muranoagent/muranoagent.conf.sample
 
 # Files created by releasenotes build
 releasenotes/build
+
+# Coverage
+.coverage
+cover/

tox.ini

@@ -23,7 +23,9 @@ commands =
 commands = {posargs}
 
 [testenv:cover]
-commands = python setup.py testr --coverage --testr-args='{posargs}'
+commands = python setup.py test --coverage \
+           --coverage-package-name=muranoagent --testr-args='{posargs}'
+           coverage report --omit '*/tests/*'
 
 [testenv:docs]
 commands = python setup.py build_sphinx