support escapeUnicode(false)

[ovoled]

There is issue #73 where escapeUnicode = false support was brought through Config.
But there is also method public static String serialize(boolean escapeUnicode, Type type, Object obj) which ignores it's direct parameter escapeUnicode.

Example:

	public static void main(final String[] args) {
		final String obj = "Привет";
		System.err.println(JsonStream.serialize(new Config.Builder().escapeUnicode(false).build(), obj)); //ok
		System.err.println(JsonStream.serialize(false, obj.getClass(), obj)); //not ok
	}

Output:

"Привет"
"\u041f\u0440\u0438\u0432\u0435\u0442"