Various fixes to handle the bundled version properly

[drebrez]

On the first run the welcome page set the php.default config as bundled https://github.com/rafajaques/php-assistant/blob/f49ae3625994bb6ebe137b012a3f978a09c3a5c1/app/js/welcome.js#L96

in app/js/binary.operations.js it reads the php.default config and expected a numeric version instead of the string "bundled".

This patch add checks for the bundled string in order to find the bundled php path, the version to show in the UI.

It also fixes an exception thrown when there aren't versions configured in the config file.

PS: with this fix and the #193 it works successfully on Windows 10 without php installed in the system.