Added UNICODE_CHARACTER_CLASS support to Regex flags. This flag is only supported in Java7 and is ignored if set on a java 6 JVM

Closes #2895
Allow PolygonBuilder to create polygons with hole

Closes #2899
Added support for the `_cache` and` _cache_key` options to the `has_child` and `has_parent` filters.
Closes #2900
Better error messaging when postings_format can be resolved or when a custom postings_format type can't be instantiated.
Relates to #2893
only return primary if it is active in PlainOperationRounting

Closes #2896