add tests for tickets app and other changes

[arminpatel]

Overview

1. This PR fixes #118 .
2. This PR does the following:
   1. Add tests for the allowed CRUD operations.
   2. Add default for status in ticket model
   3. Allow only read-only operations on status for now
   4. Allow only Create, List and Retrieve actions on Ticket.
   5. Restrict permissions for the endpoint

Essential Checklist

• [ ] The PR title starts with "Fix #bugnum: ", followed by a short, clear summary of the changes. (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• [ ] "Allow edits from maintainers" is checked. (See here for instructions on how to enable it.)
• [ ] The PR is made from a branch that's not called "main/master".

Proof that changes are correct

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