Import calendar title form iCal files. Fix #111 and Fix #123 (again)

Add no description placeholder on events without descriptions. Fix #123
Use calendar name of iCal file to prefill calendar name on imports, use cozy-ical 1.1.4 .
Fixes in sendmail confirm, during import and to maintain sending email list accurate with mails actually sent by the server.

Fix tests and avoid rebase messup of previous PR.
I do the same thing as the server do:
https://github.com/cozy/cozy-calendar/blob/master/server/mails/mail_handler.coffee#L26-L27

and so have the same email list in the popup and the sended email.

The server notify ACCEPTED guest only if the event change (which means for the server only when the start of the event change), but not when other updates occurs (like add another guest).