common: Add ObjectUtils with static methods deepEquals and deepHashCode

common: Add ObjectUtils with static methods deepEquals and deepHashCode

These methods allow equals() and hashCode() to consider arbitrary
objects which may be arrays or collections of arrays with equal elements
to be equal, recursively.

Change-Id: Ic33f6451f5b535989ad8bed1cc35095bff500b0a
Signed-off-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-on: https://git.eclipse.org/r/52187
Reviewed-by: Hudson CI
Reviewed-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Tested-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>