Add plist exception for cookbook recipes that does not support TLS 1.2

iOS9 introduces a feature called App Transport Security. By default it won't be able to make any unprotected HTTP connections; they will simply fail, and any TLS connections that your app makes will have no adhere to TLS 1.2.

If the server does not support TLS or has a version lower than TLS1.2, an exception can be handled on client side. See Apple forum discussion.

Sth like:
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
</dict>

or even more specific exception.

This is required for all cookbook recipes that use HTTP connection.