Change BoxItemCollection array in BoxItem from primitive array to ArrayList

This fixes some parceling issues, as Jackson doesn't deal with primitive arrays well.
Merge branch 'master' of github.com:box/box-java-sdk-v2 into change_boxitemcollections_to_arraylist

Conflicts:
	BoxJavaLibraryV2/src/com/box/boxjavalibv2/dao/BoxItem.java
Bump version to 3.1.3
Merge pull request #211 from box/change_boxitemcollections_to_arraylist

Change BoxItemCollection array in BoxItem from primitive array to ArrayList