Old appscale_tools namespace login in agents setup.py

[scragraham]

At the top of the setup.py script there is some legacy code related to appscale_tools. I don't believe this will cause any issues, but we should clean up the code and remove this block.

# Require users to uninstall versions that used the appscale namespace.
try:
  import appscale.appscale_tools
  print('Please run "pip uninstall appscale-tools" first.\n'
        "Your installed version conflicts with this version's namespace.")
  sys.exit()
except ImportError:
  pass