CMS-2254 Implement Item-indexing: IndexDocument to IndexSource

Added translate from IndexDocument to IndexSource
CMS-2348 Index-operations for all node-operations

Added indexing for createNode
CMS-2352 Make IndexSource as builder
CMS-2356 Make XContentBuilder use IndexDocument directly

Refactored so that indexDocument is used directly. Also added explicit support for array-values without creating invalid JSON (which actually worked but wasnt very nice)
CMS-2361 Refactor indexName to Index enum
CMS-2361 Refactor indexName to Index enum

Ops, index-name must be lowercase