Merge branch '515-merge_request_template' into 'master'

initial creation of git merge_request_templates directory.

Closes #515

See merge request platform-one/big-bang/bigbang!567

.gitlab/merge_request_templates/package_owner.md

+# Package Owner Merge Request
+
+## Package Changes
+
+What package changes are included with this merge request?
+
+The more detail here the better! **Links to the MRs that are included are required**.
+
+Also, include any issues closed with "Closes #123" where 123 is the issue number.
+
+## Additional Details
+
+If possible, provide additional details that will help with the merge request.
+
+Known issues or expected conflicts?