Use zope.testrunner in tox and travis

Life's too short to debug setup.py test.

Also fix coverage reporting to aggregate the same module installed in
different locations.

.coveragerc

@@ -1,3 +1,9 @@
 [run]
 source = z3c.currency
 omit = */test*
+
+[paths]
+source =
+   src/z3c/currency
+   .tox/*/lib/python*/site-packages/z3c/currency
+   .tox/pypy*/site-packages/z3c/currency

.gitignore

@@ -10,3 +10,4 @@ src/*.egg-info
 .tox/
 .coverage
 .eggs
+.coverage.*

.travis.yml

@@ -11,11 +11,11 @@ matrix:
           sudo: true
 
 install:
-    - travis_retry pip install .[form,test] z3c.form
-    - travis_retry pip install coverage coveralls tox zope.testing
+    - pip install .[form,test]
+    - pip install coverage coveralls zope.testrunner
 
 script:
-    - coverage run setup.py test -q
+    - coverage run -m zope.testrunner --test-path=src -vc
 
 notifications:
     email: false

tox.ini

@@ -5,11 +5,9 @@ envlist =
 
 [testenv]
 commands =
-    coverage run setup.py test -q
+    coverage run -m zope.testrunner --test-path=src {posargs:-v}
 deps =
     .[form,test]
-    z3c.form
-    zope.testing
     zope.testrunner
     coverage
 setenv =
@@ -23,3 +21,5 @@ commands =
     coverage erase
     coverage combine
     coverage report
+deps =
+    coverage