Give reasons why to migrate to alsatian

[jamesadarich]

Alsatian is great but we need to tell people WHY to move

key points:

• no globals
• smaller, simpler specs - largely due to decorators namely @TestCase
• outputs TAP
• gives you as many hints as possible (throws clear errors when things aren't set up quite right)
• code base is excellent quality (see badges) and 100% covered in tests (written in Alsatian don't you know)
• written in TypeScript for TypeScript