E-mail integration

Sometimes I get tasks by e-mails. 

It was nice if I could just hit forward on these emails, e.g. to `todo+<workspaceid>@hello.weekplan.net`.

A new task would be created with the subject of the e-mail or rather the first line of the message. The latter would be required because Gmail does not allow one to edit the subject when forwarding.

Then the content of the e-mail was attached to the new task.

E.g. one could:

1. hit forward on an e-mail,

2. add the first line: `today: Pay the electricity bill online, self` (`<date>: <task name>, <role>`),

3. send it and watch the new task created, with the contents of the e-mail attached. 

I've seen similar stuff at CRM systems.