Fix most (I hope) instances of Unable to establish a connection with SafariDriver


    Issues: #7933, #7963, #7974, 7801

    Refactor how the extension installation happens by splitting the
    installer into multiple Platform specific installers. If the installation
    still fails, provide a much more detailed explanation as to why the failure
    occurred and suggestions how to fix it.

Tested on:

* OSX 10.8.5
* OSX 10.10
* Win 7 Safari 5.1.7