fix tails logo size
Update tails logo img tag

the image has been resized, no need to have width and height anymore.
Remove old torbirdy logo, pointed out by mrphs

This also caused an issue on case-insensitive file systems.
Merge branch 'master' into staging
fix tails logo size
Update and rename README to README.md

- Applying markdown format and some prettifying.
- Adding a note to arma's instruction.
Update README.md
Update README.md

Add how to contribute
Fixing Tails logo for real!

removing jpg (which was accidentally added), resizing png to 75x75.