Update page and tt_content labels to use title case
According to http://wiki.typo3.org/TCEformsRecommendedLayout, form labels should use title case. This is mostly the case already in the backend but there are several exceptions in pages and tt_content the should be fixed.
This is not a change of meaning in the labels, since the wording doesn't change and it just follow different capitalization/punctuation rules so the existing labels are changed but do not need to be re-translated.
(issue imported from #M16989)