electron app needs polish

[rbuels]

• need to suppress error messages at the bottom of the welcome screen
• session delete buttons missing
• "Previous sessions" needs styling
• change "Previous sessions" to "Saved sessions"
• don't mention that this is desktop mode, they know it's a desktop app
• make user session names more human readable, not long paths
• fix alignment and styling of "open *" buttons
• need to have a mechanism to delete unused sessions after a certain amount of time, so that heavy users don't have old sessions piling up

some of these might be regressions

[cmdcolin]

Agree with all these items :) I guess the error message thing is since the welcome page is sort of a modification of the error page. I could either suppress the error if it's just the 404 on that data dir, or I could try and redesign the welcome so it's a different setup. Not sure which is better.

The only regression is that the session delete button is missing probably just due to css