remove intermediate "kmer" files
remove intermediate "kmer" files

It is about 10% faster to write the buffers directly into the db, provided the
db is set up for bulk loading.

abeconnelly/vg,dnanexus-rnd/vg,ekg/vg,ekg/vg,dnanexus-rnd/vg,abeconnelly/vg,ekg/vg