genomics: use thorium_actor_log in distribution and unitig manager

[boisvert@bigmem biosal]$ mpiexec -n 4 ./applications/spate_metagenome_assembler/spate -k 33 -threads-per-node 8 ~/dropbox/S.aureus.fasta.gz
[boisvert@bigmem biosal]$ wc -l log
514 log

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
unitig_walker: use thorium_actor_log

[boisvert@bigmem biosal]$ mpiexec -n 4 ./applications/spate_metagenome_assembler/spate -k 33 -threads-per-node 8 ~/dropbox/S.aureus.fasta.gz
[boisvert@bigmem biosal]$ wc -l log
60 log

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>