Removing cover.sh and folding into tox config.

This is to make the tox config friendlier to Windows
and other non-bash shells.

Towards googleapis#1123.

tox.ini

@@ -13,20 +13,29 @@ deps =
     protobuf>=3.0.0a3
 setenv =
     PYTHONPATH = {toxinidir}/_testing
+covercmd =
+    nosetests \
+      --ignore-files=run_system_test\.py \
+      --with-coverage \
+      --cover-package=gcloud \
+      --cover-erase \
+      --cover-tests \
+      --cover-branches \
+      --nocapture
 
 [testenv:cover]
 basepython =
     python2.7
 commands =
-    {toxinidir}/scripts/cover.sh --cover-min-percentage=100
+    {[testenv]covercmd} --cover-min-percentage=100
 deps =
     {[testenv]deps}
     coverage
 
 [testenv:coveralls]
 basepython = {[testenv:cover]basepython}
 commands =
-    {toxinidir}/scripts/cover.sh
+    {[testenv]covercmd}
     coveralls
 deps =
     {[testenv:cover]deps}