add request_hash/1 to riak_kv_vnode & export object_info/1

necessary to support resizing ring
make PR/PW account for forwarding during ring resizing
changes to aae to support ring resizing

* dont create trees initially when starting primaries in
a larger ring
* handle cases where exchange is enqueued for index that
exists in older, larger ring (after ring is shrunk)
dont forward gets during ring resizing

all writes are performed locally so no reason to add
extra network traffic
move bucket_nval_map/default_object_nval to core
nval_map/1 needs to be exported by vnode for ring resizing
Reduce get_my_ring calls using chashbin/etc
Optimize coverage and riak_kv_mrc_pipe using chashbin
Merge #554 from jdb-large-master into staging-1.4

Fix eunit test failures in riak_kv_vnode that were not caught pre-merge.

Conflicts:
	src/riak_kv_coverage_filter.erl
Merge #530 into staging-1.4
adjust handling of non-existent index in entropy manager
fix call to riak_core_ring_manager:get_chash_bin/0
Merge branch 'staging-1.4' to master

Conflicts:
	src/riak_kv_delete.erl
	src/riak_kv_get_fsm.erl
	src/riak_kv_put_fsm.erl