xhr.status now accepts 204 No content & 304 not modified
Let done() accept an arbitrary number of arguments

Note: modifies the join() method signature.
AJAX: pass XHR object as 3rd argument
Change join() signature

promise.join() arguments are now promises.
Make then() return a new Promise
Update docs for API changes
Remove unnecessary semi-colon
Merge vergic-master

Conflicts:
	promise.js
	tests.js
Remove unused test function
Minify lib
Merge branch 'master' of github.com:stackp/promisejs