Added formatting to README.md

Bolded name of project.
Used inline code blocks for Obj-C tokens, files, compiler flags.
First instance of `NSCache` links to Apple Developer reference.
Merge pull request #3 from Ashton-W/patch-1

Added formatting to README.md
Added lots of cool things.
Merge branch 'master' of https://github.com/nicklockwood/OSCache

Conflicts:
	README.md