[backend] refactor filter_exports function
[backend] rename %old to %oldids

... so we can have %old and %new for the package data
[backend] save meta into .meta.success

so we can rebuild :full with the correct meta
[backend] add importarch parameter to update_dst_full

In the fututre we want to store imports next to the normal binaries
in the package directory.
[backend] refactor add_binary_to_full and del_binary_from_full
[backend] set suf also for the old repo, don't delete unknown packages
[backend] do not publish non-dot files, fix bug in exporter
[backend] src server: use ajax for remote cpio source download
[api] add the possibility to subscribe to events

You can subscribe globally or on project/package leel if you want to
get notifications (not yet implemented obviously) for events either for

 - none (overwriting more global defaults)
 - project maintainership
 - package maintainership
 - all
[api] start of an action mailer for events
[api] add current hermes templates in erb format
[api] move the notification templates in the right place
[api] actually send the mail to subscribers