Create nextflow process to hmmpress marker hmms

[chasemc]

One thing I wanted to note is that currently this only works with docker as executor (ie not with conda only) because the MARKERS process requires hmmpress'ed files. @Sidduppal This also needs to be addressed in the installation documentation https://github.com/Sidduppal/Autometa/blob/documentation/docs/source/install.rst

Reference on why docker works and conda alone doesn't:

Autometa/Dockerfile

Lines 36 to 41 in 50f7a60

	RUN hmmpress -f autometa/databases/markers/bacteria.single_copy.hmm \
	&& hmmpress -f autometa/databases/markers/archaea.single_copy.hmm \
	&& mkdir -p $DB_DIR \
	&& mv autometa/databases/* ${DB_DIR}/. \
	&& autometa-config --section databases --option base --value ${DB_DIR} \
	&& echo "databases base directory set in ${DB_DIR}/"

Originally posted by @chasemc in #157 (comment)

[chasemc]

Nextflow module will need to be changed (is Docker image specific):

Autometa/modules/local/markers.nf

Lines 44 to 45 in 36d52b1

	--hmmdb "/scratch/dbs/markers/${params.kingdom}.single_copy.hmm" \\
	--cutoffs "/scratch/dbs/markers/${params.kingdom}.single_copy.cutoffs"