Fix calls to nonexistent functions

Refactorings in the erlang-oauth dependency broke
`couchbeam_util:oauth_header/3`, as the called functions aren't
available anymore.

For reference, here the "breaking change" in erlang-oauth:

https://github.com/tim/erlang-oauth/commit/fc5f528cea05b6b0b5e3ace0300268a330b01ac6
Merge pull request #90 from KlausTrainer/fix-function-calls

Fix calls to nonexistent functions
Use tagged versions of dependencies
Merge pull request #91 from KlausTrainer/use-git-tags

Use tagged versions of dependencies
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
use JSX as default encoder/decoder

This commit makes the following changes:

- JSX is now the default encoder
- remove mochiweb and JIFFY from the dependencies
- JIFFY can be used as the default encoder by defining `WITH_JIFFY`
  during the compilation.

fix #95
only test for R15B03 and sup.