Added icon to web interface

[MagicLike]

Description

I added an Twemoji as an icon for the web interface & updated the README with the licence attribution.

Fixes #57

Type of change

• Bug fix (added a non-breaking change which fixes an issue)
• New feature (added a non-breaking change which adds functionality)
• Updated documentation (updated the readme, templates, or other repo files)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• Ran tests with composer test
• Added or updated test cases to test new features

• Tested on own Heroku instance

Checklist:

• I have checked to make sure no other pull requests are open for this issue
• The code is properly formatted and is consistent with the existing code style
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

Screenshots

[MagicLike]

I know it's pretty simple, but I think that it could be used until a proper logo or something else is made.

[DenverCoder1]

This looks great!

Possibly we could change the name of the file from2328.png to something like favicon.png?

[MagicLike]

Done. 👍

[DenverCoder1]

Looks great! Thanks for the contribution 🎉