Fix typo
Add TODO
Add explanations for the snapshot repository
Remove details on the raven-legacy project
Remove details on the jetty issue
Document the default enabled async mode
Tags are not supposed to be a set of strings

Each tag is supposed to have only one value as a String.
If tags are sent as a map of arrays, the displayed value will be the
"stringified" version of the array in Sentry. ie: [u'value']
Merge branch 'master' into raven-3.x