add not_found error to validate_doc_read function
s/not_found/notfound/g
icorrectly handle not_found error from validate_doc_read
add missing db "created"  event
api to retrieve the VM stats

Code to expose the vm stats to couch_stats. For now just steal the code
from Folsom (https://github.com/boundary/folsom). HTTP api to expose it
is coming in another commit.
expose vm stats to the HTTP api.

GET /_stats/vm/system : system info
GET /_stats/vm/memory : memory info
GET /_stats/vm/port : ports info
GET /_stats/vm/process : process info
GET /_stats/vm/ets : ets info
GET /_stats/vm/dets : dets info
Revert "on changes, remove the connection from the pool."

This reverts commit 8d6f71e79c8382e83e9587b0d81991ec955d34bb.
use rcouch branch orf ranch
get the number of running connections

GET /_stats/httpd/connections
workaround to prevent the view changes reader to crage on non found doc

when a doc is removed from the database in the current version of the
view changes index, this change is not indexed and the view change index
has still the key indexed. The way to delete for now is to use
include_deleted=true and push deleted doc that match the view so the
deleted document can be indexed as deleted.

But when the doc is purged and someone fetch the changes the view
changes reader was crashing because it didn't find the doc. This
workaround patch the changes reader to ignore the documents not found
and simply log them.
Merge branch 'master' into release/0.7.x

- fix ranch dep

Conflicts:
	apps/couch_httpd/rebar.config