jQuery 1.8.2 and 1.8.3 support

[jalexanderfox]

I recently tried using jquery-postmessage with jQuery 1.8.3 and 1.8.2 and found that those versions appear to break this plugin, but it does work with jQuery 1.8.1. For now I am just using jQuery 1.8.1, as my use case is isolated from a larger site.

[slavafomin]

There is a problem with jQuery 2.x. Looks like we will have to use a native implementation before this plugin will be updated.