Add title field to submission model

[TimJentzsch]

Relevant issue: Closes #149.

Description:

Adds an optional title field to the submission model and allows filtering and ordering by title on the submission view. This allows us to fetch the title directly from Blossom instead of having to get it from Reddit.

Checklist:

• [x] Code Quality
• [x] Pep-8
• [ ] Tests (if applicable)
• [x] Success Criteria Met
• [x] Inline Documentation
• [ ] Wiki Documentation (if applicable)