initial work to replace ibrowse by hackney in couchbeam
miscellaneous fixes.

only view tests don't pass for now.

t/001-load.t ........ ok
t/002-server.t ...... ok
t/003-database.t .... ok
t/004-document.t .... ok
t/005-view.t ........
t/005-view.t ........ Failed 5/5 subtests
t/006-attachment.t .. ok
add the couch view stream
port views to hackney

all tests pass now

t/001-load.t ........ ok
t/002-server.t ...... ok
t/003-database.t .... ok
t/004-document.t .... ok
t/005-view.t ........ ok
t/006-attachment.t .. ok
All tests successful.
Files=6, Tests=61,  3 wallclock secs ( 0.08 usr  0.02 sys +  2.35 cusr
1.10 csys =  3.55 CPU)
Result: PASS
row is already an object
remove spurious prints
test for R15 and R16
fix view folding
couchbeam_changes is now based on hackney

- stream and fetch functions has been removed and replaced by follow and
  follow_once.
- New events are {Ref, {change, Change}}, {Ref, {done, LastSeq}}
simplify the API.

Most of the time messages are expected to be received on the same
process. this change make it the default. now to stream to another pid
the option `{stream_to, Pid}` should be used.
sync doc
typo
improve the doc
Merge pull request #94 from benoitc/hackney

replace ibrowse / hackney