Bug 7521: Convert install snapshot chunking to use streams

Bug 7521: Convert install snapshot chunking to use streams

On the leader side, converted LeaderInstallSnapshotState to use
the InputStream from the ByteSource instead of a ByteString to
chunk the data.

On the follower side, converted the SnapshotTracker, which is used
to reassemble the install snapshot chunks, to write the chunks to
an OutputStream instead of a ByteString. Currently a
ByteArrayOutputStream is used by will be changed to a
FileBackedOutputStream in a subsequent patch.

Change-Id: I7a16ad5d44a530e260aa332d91145fbc3fb95f5f
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>