Koji tag validation

- Decorator supporting str/list args
- ProgrammingError exception which may uncover typos in the names of args to validate
- Configurable whitelist of koji tag prefixes
- Add basic validation to test_build.TestModuleBuilder

conf/config.py

@@ -31,6 +31,7 @@ class BaseConfiguration(object):
     KOJI_ARCHES = ['i686', 'armv7hl', 'x86_64']
     KOJI_PROXYUSER = True
     KOJI_REPOSITORY_URL = 'https://kojipkgs.stg.fedoraproject.org/repos'
+    KOJI_TAG_PREFIXES = ['module']
     COPR_CONFIG = '/etc/module-build-service/copr.conf'
     PDC_URL = 'http://modularity.fedorainfracloud.org:8080/rest_api/v1'
     PDC_INSECURE = True