timeout insufficient for manual install on standard VPS servers in unicorn.rb

When installing GL, the first request sent to the server (to set up admin access) takes a very long time. In fact, on a standard linode VPS server, it takes about 100 seconds.

But the default timeout is only 30 seconds in config/unicorn.rb. When the server times out, it creates an error that's very hard to track down, especially for those of us who aren't professional server admins. The user simply sees a nondescript 502 error, and the logs say something ambiguous like "can't connect to socket."

Based on this stackoverflow question, which took me a while to find, this has been a problem for over a year.

At least one the following should be done:

• The manual install documentation should be changed to specifically warn of this problem, in the comments above the line sudo -u git -H editor config/unicorn.rb
• The default timeout in config/unicorn.rb should be increased to, say, 120 (I understand this is high, but that's better than breaking the install).
• The 502 page should recommend increasing the timeout in config/unicorn.rb (and perhaps other troubleshooting tips).