Baolinh/chat character limit

Types of changes

[ ] Bugfix (change which fixes an issue)
[x] New feature (change which adds functionality)
[ ] Refactor (change which changes the codebase without affecting its external behavior)
[x] Non-breaking change (fix or feature that would causes existing functionality to work as expected)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Added character chat limit to be displayed in the chat box. This now enforces a 255 character limit on messages sent.

[x] My branch follows the branch naming scheme of UCLA Radio, and can merge into master without error.
[x] My code follows the code style of this project, and I have linted it to confirm this.
[ ] I have added tests that prove my fix is effective or that my feature works.
[ ] My change requires a change to the documentation and I have updated the documentation accordingly.
[x] All new and existing tests passed.