addressing translatewiki requirements

* Sentence cased messages as much as possible.
* removed wikitext syntax within messages, except for bold and italic syntax
* removed PHP_EOL

addressing raimonds’s additional comments
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* adding <code> around variables in messages
* naming consistency -> URL, XML, JSON, MediaWiki
* correcting sentence casing
* removing spaces between : and word and trailing space
Change-Id: I220442020c46edee1bbf336383aad79ca0dea5d0