test/ -> tests/
some restructuring / added "put" and "delete" methods
public methods are renamed to "xhr<HTTP_METHOD>". available at the moment: xhrGet, xhrPost, xhrPut, xhrDelete, xhrHead
only one callback function is possible now iwth three parameters: data, statusCode, statusText
initial commit
changed callback functions, because its only one possible now / added tests for xhrPut and xhrDelete
added different responses for each HTTP method