PIVOT-799: Improve operation of Pivot collections objects.

This is just a part of what could be done, according to the issue:
Add constructors for ArrayList and HashMap that take java.util counterparts.
* new ArrayList(java.util.Collection<T>) constructs a new Pivot list from the
  existing Java list.
* new HashMap(java.util.Map<K,V>) constructs a new Pivot map by copying the
  existing Java map.


git-svn-id: https://svn.apache.org/repos/asf/pivot/trunk@1587756 13f79535-47bb-0310-9956-ffa450edef68