Added a version of knockout.d.ts for AMD compilation (i.e. RequireJS).  Compiles in TypeScript 0.8.3 and will probably compile in 0.9.0 final (as of TypeScript 346c054bba830d566bc18c1e998cde327704fee4 it throws up when the template section at the bottom is included).

Haven't done any tests or anything...
Removed extraneous duplication, fixed building with 0.9.0
Merge pull request #572 from diachedelic/master

knockout module definition