Pulling back ACCUMULO-1672 changes from master.
ACCUMULO-1639 Adding ColumnSliceFilter implementation from Jeffrey Principe.

The implementation filters out records which do not fall between a given column
qualifer range. It is intended to be equivalent functionality to HBase's
ColumRangeFilter.
ACCUMULO-1639 Merge branch '1.4.5-SNAPSHOT' into 1.5.1-SNAPSHOT

Includes a move to account for src/core/->core/