v1.5.2-rc56 - include decoded image dimensions with job result

• job_result and build_result JSON nodes now include a "decodes" entry next to the "encodes" entry, with the same schema
• v1/get_version_info now includes git_tag and git_describe_always entries. git_tag is optional.

Note: this release is the same as 1.5.1, but due to deployment issues 1.5.1 was not fully released.