Add disk stats to `/stats` output to make consistent

As pointed out by @fygrave in #285, `riak-admin status` shows
diak stats, but `/stats` does not. This fixes that.#285, `riak-admin status` shows
diak stats, but `/stats` does not. This fixes that.#285, `riak-admin status` shows
diak stats, but `/stats` does not. This fixes that.
Handle worker errors and timeout on 2i reformat

Before this fix, I noticed the reformat basically hang forever with a
crashed worker error once. This fix handles the error message from the
vnode worker and adds a big 2 minute timeout to make sure we don't get
stuck. In reality, it's mostly harmless, but annoying to leave a process
hanging forever like that.
- pull in sbv's param mods drop with some additional porting
  make it compatible with 1.4 features.
- export some opaque types
- change some crypto hash functions to remove warnings
Merge pull request #383 from basho/rdb-eq-stats-status

Add disk stats to `/stats` output to make consistent
Merge pull request #561 from basho/eas-2i-reformat-handle-error

Handle worker errors and timeout on 2i reformat
updates to restore R15 compatibility
Move json encoding out of riak_object

Revisiting https://github.com/basho/riak_kv/pull/88
But using riak_object_json encode/decode and leaving old methods in
riak_object.erl with a deprecation warning.
add explanitory comment
Remove -author attributes

They aren't kept current and the same information can be ascertained
from git.
Merge pull request #603 from basho/rz-remove-authors

Remove -author attributes
Addressing review comments

Using constants for links and last modified headers.
Removing old @spec.
String detection should not allow 256 int values.
client fix to stop breaking put/2
make eqc build again
reverse macro logic to favor forward compatability
Switch from Makefile to rebar.config.script for old_hash define
One missed new_hash ifdef
resolve author attribs conflict
Merge branch 'pevm-r16-compat2' of github.com:basho/riak_kv into pevm-r16-compat2
Merge pull request #602 from basho/pevm-r16-compat2

R16B01 compatibility changes.
Make the memory backend config behave as documented

Also, fix yessir backend, which has the same potential issue.