Say "CERN" instead of "Cern"

It's an acronym, and this is how they style it on http://home.web.cern.ch/.
Refer consistently to the language as "Python"
Fix "differnt" typo
Fix "anythng" typo
Mark up more inline code
Merge pull request #5 from CodeClub/fix-typos

Fix a few minor typos in lesson 1
add how to do colours in hex, fix some typos/grammar

decided not to do colours in rgb as for some reason they take values between 0 and 1, not 0 and 255 and it seemed a bit much to introduce in the first lesson, but the kids should be familiar with hex form CSS
change lesson 02 to introduce fills and functions