Random number seed for SWAPSHOP

I have added a random number seed to SWAPSHOP so that the results are reproducible. 

Changes are as follows:

1) Add an extra argument to SWAPSHOP.csh which takes as input a random seed. However it only works when startup is specified.
2) SWAPSHOP.csh runs the program generate_random_state.py to generate a random state file from the seed provided by the user.
3) The config files have an extra compulsory option (random_file) which is the name of the file which stores the pickled random state.
4) SWAP.py stores the random_state in a the random_file at the end of a run when update.config has to be written.

Please review the changes before merging. I have not tested the code as I do not have mongod running on my computer.