in contrib/securityLib/jsbn.js:

- use var BigInteger instead of function BigInteger (fix odd 'undefined' error)
in contrib/securityLib/jsbn2.js:

-define exports.BigInteger and module.exports = exports (waf + browserify pattern)
in contrib/securityLib/rsa.js:

-add 'intShim' and detect presence of .BigInteger (bridge differences between browserify require and waf require)
-define RSAKey with var instead of function (fix "RSAKey 'undefined'" in browserify)
-define exports.RSAKey and module.exports = exports (waf + browserify export pattern)