Create symlink to `allpairs_multicore`

Without this the prepare step of both allpairs tests fail on OS X with 'allpairs_multicore not in path' error.
New method for allpairs test.

Check that each input file occurs n times (where n is the total number of input files) in the first two columns of the output, which is the expected pattern for an allpairs run.
remove 'horrible, horrible' testing method
remove makeflowlog generated during testing
Merge pull request #5 from rampantmonkey/test_cleanup

Test cleanup for bitwise allpairs.
The code that handles sending input files is now refactored into 4 functions:
1. put_input_item() which replaces put_file() from before
2. put_directory() which sends mkdir() to worker and sends its contents by
calling (recursively) put_directory() or put_file()
3. put_file_whole() which sends the entire file contents to worker
4. put_file_piece() which sends the file contents within specified byte offsets.

This fixes Bug 993: Cached and Uncached directories in work_queue_worker.