Fix plugin config so conduit conf methods work.

The BaseConduit config getters never worked. So
for any use other than existence of [main] and
checking enabled=1, plugin config would fail.

The test cases were providing a ConfigParser
to BaseConduit to use for it's self._conf instead
of a PluginConfig class. So BaseConduit._conf.getint
existed for tests, but not for actually use, where
BaseConduit._conf was a PluginConf, and needs to
call BaseConduit._conf.parser.getint()

Make test cases use a PluginConf and add more
config related test cases.
Merge pull request #956 from candlepin/alikins/fix_plugin_conf

Fix plugin config so conduit conf methods work.