Fixing accidental removal of {localdeps}

Also

- adding RTD  dependency for runtimeconfig.
- adding local paths to umbrella tox config "deps"
  as was done in #2733.

Author: dhermes

packages/google-cloud-language/tox.ini

@@ -17,6 +17,7 @@ covercmd =
 
 [testenv]
 commands =
+    {[testing]localdeps}
     py.test --quiet {posargs} unit_tests
 deps =
     {[testing]deps}
@@ -25,6 +26,7 @@ deps =
 basepython =
     python2.7
 commands =
+    {[testing]localdeps}
     {[testing]covercmd}
 deps =
     {[testenv]deps}