Remove Job from implemented entities list

It's not necessary, as Customers are now Jobs if certain attributes are
set.

More info:
https://developer.intuit.com/docs/0025_quickbooksapi/0058_faq/qbo_v2_to_
v3_migration_guide#Jobs_%28subcustomers%29
Merge pull request #35 from harvesthq/remove-job-from-readme

Remove Job from implemented entities list