1087 correct indefinite article for oms

added new gem and used its method 'with_indefinite_article' for all the found instances where it can be applied.
Here is the indefinite_article in the text and the gem should add this by itself so its an duplicate(e.g. "an an ontology") of this in the text. The line break here is wrong. Pleas remove all linebreaks in strings which you have in this pullrequest.