tox.ini: Updated [testenv:cover] so that coverage generates a report

Also added omissions in .coveragerc to ensure that the report doesn't
test tests, nor __init__.pys.

Change-Id: I5f816b9a030e3941c6e38ea5610047aa6f93b6f8

.coveragerc

@@ -0,0 +1,4 @@
+[run]
+omit =
+  networking_vpp/tests/*
+  */__init__.py

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.0
-envlist = py35,py34,py27,pep8
+envlist = py35,py34,py27,pep8,cover
 skipsdist = True
 
 [testenv]
@@ -13,6 +13,7 @@ passenv = TRACE_FAILONLY
 install_command = {toxinidir}/tools/tox_install.sh {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
+       coverage
 commands = ostestr --regex '{posargs}'
 
 [testenv:pep8]
@@ -22,7 +23,9 @@ commands = flake8
 commands = {posargs}
 
 [testenv:cover]
-commands = python setup.py test --coverage --testr-args='{posargs}'
+commands =
+  python setup.py test --coverage --coverage-package-name='networking_vpp' --testr-args='{posargs}'
+  coverage report
 
 [testenv:docs]
 commands = python setup.py build_sphinx