Merge pull request #1 from shrikrishnaholla/dev

Update from dev branch
Add .DS_Store to .gitignore
Merge pull request #2 from srinidhij/login

Phase 2 complete
Added missing route for submitting notes
Change input field of usn from `disabled` to `readonly` so it gets submitted
Added models for comments
Support for adding comments
Routes for viewing and posting comments
Frontend for viewing and posting comments
Add links to view comments for each note
Merge pull request #6 from srinidhij/master

Added backend  for comment system