Add missing taxranks that appear in NCBI Taxonomy Database

[cthoyt]

Closes #4

This PR adds the ranks that appear in the NCBI Taxonomy Database to TAXRANK. Here's a table that shows the impact of each of these terms, where the count is how many distinct NCBI Taxa have this rank. I then ran make and make prepare_release after.

Note: I also did a bit of housekeeping in this PR too to add the license and contributor list.

NCBI Rank	CURIE	Count	Example	Example Name
strain	NCBITaxon:strain	46478	NCBITaxon:355	Azotobacter chroococcum (strain mcd 1)
isolate	NCBITaxon:isolate	1305	NCBITaxon:5838	Plasmodium falciparum FCR-3/Gambia
serotype	NCBITaxon:serotype	1229	NCBITaxon:10510	Bovine adenovirus 3
clade	NCBITaxon:clade	963	NCBITaxon:3193	Embryophyta
forma specialis	NCBITaxon:forma_specialis	785	NCBITaxon:5508	Fusarium oxysporum f. sp. cucumerinum
serogroup	NCBITaxon:serogroup	154	NCBITaxon:491	Neisseria meningitidis serogroup B
genotype	NCBITaxon:genotype	22	NCBITaxon:33745	Hepatitis C virus genotype 4
biotype	NCBITaxon:biotype	17	NCBITaxon:725	Haemophilus influenzae biotype aegyptius
morph	NCBITaxon:morph	11	NCBITaxon:304407	Acontias orientalis morph lineacauda
cohort	NCBITaxon:cohort	5	NCBITaxon:33341	Polyneoptera
pathogroup	NCBITaxon:pathogroup	5	NCBITaxon:1982676	Xanthomonas axonopodis subcluster 9.1
subcohort	NCBITaxon:subcohort	3	NCBITaxon:32519	Ostariophysi

[cmungall]

LGTM

[hlapp]

Nice 👍

[hlapp]

@cthoyt any chance you can add the OWL conversion?

[cthoyt]

@hlapp I ran make and make_release as instructed in the README-editors file and committed the two updated files in 0527d24. Since this repository doesn't have contributing guidelines, I wasn't sure if this was something I should do or not

[hlapp]

Awesome, thanks so much @cthoyt. I agree there should be a contributors template. I'll make that an issue so it can be tracked.

[hlapp]

@balhoff are you handling new release etc?