Ensure writeBufferLoad test is fully deterministic

[lundgren87]

Related to the discussion in:
#45 (comment)

The goal of this test is to ensure that, regardless of the number of ArgoDSM nodes and the future allocation policy used, pages appear in a non-sorted order in the write buffer. This allows for testing that we protect ourselves against interleaving locking (as opposed to locking windows on node 0, 1, 2, ..., n in order) of remote MPI Windows producing deadlocks.

The current implementation relies on producing enough random writes to ensure that this scenario is likely to always trigger, but a sequence of numbers or a seed that guarantees such a result would be a better solution.