Improve usability SSO flow

Currently when you use SSO you have to input the team name. A couple of things that make this hard to use:

• The team name was configured automatically at first, making this a long strange name. There's no way to view the complete team name, or to copy it. Only support can change this name.
• The team name input field is capital sensitive. This makes it hard for users to input the right name, as they might not use capitals in the right places. It's also irrelevant to keep capitals in mind here.
• A more common approach is to ask users for their email address, and derive the right login page from that. Email is something users know, and it reduces the guessing game for the right team name (e.g. is it our company's full name or shorthand? Do we include our domain or not?)