Update composer.json

Moved the PHP version requirement to main require statement. You want to enforce this system wide, not just in development mode.
Merge pull request #3 from marcqualie/patch-1

Update composer.json
Composer version requirements (thanks @marcqualie)
Update README install syntax

Doing it this way means users get the latest stable 1.x branch whenever they upgrade. It also means you don't have to update the README each time you do a minor fix.
Merge pull request #4 from marcqualie/patch-2

Update README install syntax
Added Marc Qualie to contributors
Updated README.md … how tired was I when I wrote it?!
Merge pull request #5 from marcqualie/patch-3

Added Marc Qualie to contributors