Output results files on jenkins

Outputs:
 * results.xml
 * coverage.xml
 * violations.flake8.log

tox.ini

@@ -11,8 +11,8 @@ deps =
 setenv =
     PYTHONDONTWRITEBYTECODE = no_byte_code
 commands =
-    /bin/bash -c "coverage run --source=synapse {envbindir}/trial {posargs:tests} {env:TOXSUFFIX:}"
-    coverage report -m
+    /bin/bash -c "coverage run --source=synapse {envbindir}/trial {env:TRIAL_FLAGS:} {posargs:tests} {env:TOXSUFFIX:}"
+    {env:DUMP_COVERAGE_COMMAND:coverage report -m}
 
 [testenv:packaging]
 deps =
@@ -25,4 +25,4 @@ skip_install = True
 basepython = python2.7
 deps =
     flake8
-commands = flake8 synapse
+commands = /bin/bash -c "flake8 synapse {env:PEP8SUFFIX:}"