Hotfix needed for errors in health-lifesci and pending Course definitions

[danbri]

Thanks to #1168 we can belatedly catch some bugs in extension definitions. These are in the health-lifesci definitions (/cc @twamarc) and the pending draft for courses (/cc @philbarker #195), and the health-related pending proposal #1062 for ushealthcare descriptions (/cc @vholland).

I will simply comment out all the corresponding domain/range assertions for now, except for Url -> URL.

I note for courses we ought to talk about whether 'credential' and 'certificate' work well as names; to a broader tech audience they could look like crypto terminology rather than educational.

1.)
test_validDomainIncludes (test_graphs.SDOGraphSetupTestCase) ...

1a.
INFO:test_graphs:Property http://schema.org/bodyLocation invalid domainIncludes value: http://schema.org/MedicalSpecimen

1b.
INFO:test_graphs:Property http://schema.org/drugUnit invalid domainIncludes value: http://schema.org/DrugDispense

FAIL

2.)
test_validRangeIncludes (test_graphs.SDOGraphSetupTestCase) ...
2a.
INFO:test_graphs:Property http://schema.org/benefitsSummaryUrl invalid rangeIncludes value: http://schema.org/Url
2b.
INFO:test_graphs:Property http://schema.org/grantsCredential invalid rangeIncludes value: http://schema.org/Credential
2c.
INFO:test_graphs:Property http://schema.org/healthPlanMarketingUrl invalid rangeIncludes value: http://schema.org/Url

FAIL