Sentry Issue: KAP-5KT

TypeError: Cannot read property '1' of null
  File "app:///main/utils/encoding.js", line 17, in getEncoding
    return /.*: Video: (.*?) \(.*/.exec(error.stderr)[1];

Expected behavior

The identity for forwarding an email should be selected from the recipients of the original email. This is similiar to #935 but for forwarding

Actual behavior

The default identity is used.

My proposal:

Include Action.FORWARD and Action.FORWARD_AS_ATTACHMENT to the if-condition here: https://github.com/k9mail/k-9/blob/b9eba6971fa86b95a4855caddbfa7144e5c238

In osx/updater/updater.go, we're referencing an ancient Go package, which has moved to a new location. Right now, the updater doesn't build (should we test this on travis?).

The visual appearance of the reconnect error page we see when there are problems with the internet connection can be significantly improved.

• Clear steps to reproduce the issue:
  Start the app without an internet connection