job-password, job-password-encryption, job-release-action support

[michaelrsweet]

Split this out from issue #15

Add support for the EPX2 versions of Release Jobs using job-password/-encryption and job-release-action:

• [ ] Add support for job-password, job-password-encryption, and job-release-action
• [ ] Add pappl_jreason_t bits for the release job sub-states
• [ ] Add bitfields for these attributes to the pappl_pr_driver_data_t structure, with corresponding enums
• [ ] Add private mapping functions to/from the enums
• [ ] Add values to pappl_pr_options_t structure
• [ ] Implement web interface callback in test driver