introduce very slight gradient for message header to get rid of hard border

remove 'Check messages' button and add scroll-to-refresh and shortcut

move GitHub specific files to .github and add issue details sections

Keep unread/total message counter in sync when reading/deleting messages

bump supported core version to 9.2

Update "Resetting the app"

also drop the table `oc_mail_collected_addresses`.

use 'mail' instead of 'Mail' for bower to prevent warning

Enhanced keyboard event handling + new shortcuts

smoother transition when adding another account

remove obsolete folder reset event + event handler

use underscore to debounce search filters; do not re-search the same …

update/unify license headers

0.5.3 version bump

update grunt

open first mailbox when clicking the account's email address

Message Backbone model/collection