Test to check if the source submission is retained in memory

This is a first pass at an automated test to check for the submission in the memory dump of the source process.

- Shelling out to gdb is a little ugly (submission_not_in_memory.py:17). We might be able to do it in pure python using /proc/<pid>/maps and /proc/<pid>/mem as described here: http://unix.stackexchange.com/questions/6301/how-do-i-read-from-proc-pid-mem-under-linux/6302#6302

- It could be reasonable to allow the submission to be in memory immediately after it's submitted, in which case we could add a couple submissions (with different content) before checking for the first one. Waiting for a period of time or forcing a python gc are other options.

Anyway, this should already be useful to anyone working on iSEC-14FTC-003-9

This currently fails (for good reason), so I haven't added it to the build.