Add Thumbs.db to the ignored files.
Introduce an images directory and add 2 images.

The first image consists in a bug icon, and the other one is the logo
which is going to be placed in the header. Both images are in PNG
format, and have been shrinked through TinyPNG.
Add sftp-config.json to ignored files.

This file is automatically generated by the SFTP plugin of Sublime Text,
and contains important credentials.