More text changes, mainly related to capitalisation.

While I'm here, I'll just tweak a few words. Feel free to pick and choose. Generally speaking, the rules regarding capitalisation are to only capitalise the first letter of a sentence, of proper nouns (e.g. "Android Jelly Bean"). For example, "App" should probably be lower case in most places. I also tried to explain "Allow Gap Search" in the description, but may have failed.