Rename BioSample to Biosample

[david4096]

This suggestion closes #684 by removing the capitalization from sample. This is a welcome change that better follows common conventions. Thanks @mbaudis !

[mbaudis]

+1 Obviously. Thanks @david4096!

This was one of the issues which had been discussed before, but probably succumbed to branching madness^TM.

[dcolligan]

+1

@david4096 you can probably rebase and merge this now... small change that's been open for a month with no objections

[david4096]

This will introduce breaking changes to the compliance suite, I believe. Let's wait to merge until we can verify.

[ejacox]

Pull doc/source/metadata_schema.png from my branch (biosample-1394, commit 0b2745f) to get the updated png file.

[david4096]

Thanks @ejacox got it!

[david4096]

@ejacox updated