Implicitly add "/** @jsx React.DOM */" when using JSXBundle. Fixes #31

Also use the same ConcatenationToken as used in the ScriptBundle class.
Documentation (Bundle.ConcatenationToken): "Gets the token inserted between bundled files to ensure that the final bundle content is valid. By default, if ConcatenationToken is not specified, the Web optimization framework inserts a new line."

The derived class ScriptBundle, Microsoft has this line to prevent unexpected behavior when a JavaScript file is not closed with ;