Fix newline sensitive behavior

Allows `mvn verify` to complete successfully on Windows (JDK7 and Win7, at least). The only issues were around newlines.

JsonGenerator.useDefaultPrettyPrinter() uses DeafultPrettyPrinter, which outputs System-dependent newlines. Use our own which and always output '\n', which fixes tests and makes REST more consistent to boot.

Also be a little smarter in the Strings helper that requests newlines be preserved (i.e. don't convert them accidentally).

Fixes #753