Check that all parts of installation procedure complete successfully

[choksi81]

When the installers fail to download, our downloadandinstall integration test does not recognize that and proceeds on working on the test, giving us a seemingly unrelated error:

[Jan  3 16:45:04 2014](Fri)Exception: failed to open/read/eval vesseldict file
Error: IOError
Description: [2](Errno) No such file or directory: '/home/integrationtester/seattle/seattle_repy/vesseldict'
Traceback:
  File "/home/integrationtester/cron_tests/downloadandinstallseattle/downloadandinstallseattle.py", line 163, in main
    f=open(prefix + "/seattle/seattle_repy/vesseldict", "r")

Looking at the source file, it is littered with a lot of invocations of common shell utilities. We should change these to be python calls (or do a little more checking) to verify that all the steps in the installation procedure actually succeed.

This is one example of invoking a program without doing error checking:
https://seattle.poly.edu/browser/seattle/trunk/integrationtests/downloadandinstallseattle/downloadandinstallseattle.py#L116