Removes Xcode install step

It seems that all we need are the command line tools installed.

Also:
- Updated the gem install step to use sudo for the bundle 
  since the expectation is that they are running on system ruby
- Updates the expected time it takes to do a full soloist 
  run from 2-3 hours to 10 minutes to 2 hours because it seems 
  to take about that long these days if one has a good network 
  connection.