fix couch_htppd boot
forgot to register couch_httpd
fix syntax
only crash the acceptor loop on R15
build with debug infos
graceful reload of the configuration
use ranch:start_listener
forgot to save this change
fix issues with ranch

couchdb has a tendancy to exit from anywhere (old mochiweb design). Make
sure we can really recover from crashes by returning ok when it happen.
We still have some logs due to ranch  but that better than the old
situation.

side note: we are now based on latest stable branch of ranch.
this is not about you. just me and that protocol.
allows replication logs to be saved in their own file
quick fix for r16b01
on changes, remove the connection from the pool.

Changes connections are generally long-lived conections, keeping them in
the pool limit the number of concurrent connections. This change fix it
by removing them from the ranch connection ssupervisor once the changes
connections are accepted.
remov gstatb flag

temporary fix waiting the new rebar plugin
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
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.
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.