Yellow vs Grey code

:warning: More opinions needed before merging :warning: 

@mikokim Wanted to change the yellowish background of inline code and code blocks to light grey instead of yellow. It would look like this:

![grey](https://f.cloud.github.com/assets/378023/1670557/3e868646-5c9b-11e3-8108-7228658468db.png)

And the two compared:

![compare](https://f.cloud.github.com/assets/378023/1670561/4aafc7ac-5c9b-11e3-8962-01f59caa6741.png)

His argument is that it would be easier to quickly scan the text.

I @simurai prefer to keep the yellow. With the argument that it's easier to see what is code and what is text. It also matches better with the syntax highlighting we're using.

Anyone has a preference?