charm-event messages not included in store-missing listings

[Aaron Bentley]

When a charm could not be published in the store, there is often an explanatory message in charm-events. For example, https://store.juju.ubuntu.com/charm-event?charms=cs:~ce-orange-squad/precise/jenkins-launchpad&stats=0 indicated that option defaults were unacceptable. The store-missing page should list such messages, so that it is easier to determine why a charm is missing from the store.