Add mkical tox environment for ease of use

Generating the ical files from YAML requires
runtime dependencies to test, which we can easily get
with a tox environment. This makes it easier to test
the current state of the project with a single command.

Change-Id: I6583613aa89e766da5cd0d2824741c89e74c558c

tox.ini

@@ -12,6 +12,10 @@ commands = flake8
 [testenv:venv]
 commands = {posargs}
 
+[testenv:mkical]
+commands = mkdir -p ical
+           python arbiter/jobs.py -i ./ical -c
+
 [flake8]
 show-source = True
 exclude = .venv,.tox,dist,doc,*.egg