Added support for text colours other than black

Signed-off-by: Matthias Stevens <matthias.stevens@gmail.com>
Added containsOneOf(params) method to Parameters

Signed-off-by: Matthias Stevens <matthias.stevens@gmail.com>
Refactored to way we deal with captions on Fields and especially on ChoiceFields:
- captions can now be null on Fields (meaning they are no longer always replaced by the id when missing, although some subclasses still do this)
- improved Field helper methods to convert id's into captions and vice-versa
- got rid of "alt" attribute on ChoiceFields, parser now parses it as a caption (but only if there is no "caption" attribute too) but will use a default captionHeight of 0 to hide it by default and only show it instead of a missing image (thereby emulating the old "alt" behaviour)
- refactored the logic which determines the appearance of ChoiceField Itemq in AndroidChoiceUI (and ChoiceUI)