ABPSC — Formalize language requirements in our templates

The OMG working language is British and Commonwealth English, as this is the required language for ISO specifications. For consistency we have carried this language policy through to the RFP, which does not go through the ISO PAS process. Meanwhile not all RFC are expected to go through ISO.

At present, our RFP Template uses the alternative British endings of 'ise'. whereas ISO requires that also-British 'ize' endings on certain (not not all) kinds of words that take 'ize' in the US.