Work on meeting flow

[JakubKoralewski]

JakubKoralewski/lets-watch-it-together#14

[Yurii17K]

Creating a meeting feature using google calendar.
USE CASE:

1. User chooses a date, a person to invite.
2. Adds a meeting to his/her Google Calendar.
3. An invite is automatically sent thanks to google calendar.
4. An invitee either adds the meeting to his/her calendar or not. If not our user gets a decline and plans a new meeting.