Function to calculate remaining bytes in a payload

This can be used to determine how long the alert string can be without
going over Apple's 256-byte limit.
Merge pull request #4 from eleostech/payload-size

Function to calculate remaining bytes in a payload
-specs for binary arguments
Merge pull request #5 from unisontech/specs_for_binary_arguments

-specs for binary arguments
Update for R16B.
Merge pull request #6 from lechat-im/master

Update for R16B
Removed tests directory from rebar.config edoc options.
Merge pull request #7 from inaka/inaki-docfix

Removed tests directory from rebar.config edoc options.
Renamed test directory to /test from /tests
Cleanup of Makefile for consistency.

Removed use of deprecated rebar options for running build_plt and dialyze.
Removed update-deps target.
Made xref verbose.
Merge pull request #8 from inaka/inaki_makefilefix

Inaki makefilefix
Enabled cover in rebar.config, added cover.spec
Merge pull request #9 from inaka/inaki_add-cover

Enabled cover in rebar.config, added cover.spec
not logging push payload
allow adding extra staff into apn msg
Merge pull request #1 from georgeye/master

allow adding extra staff into apn msg
Merge pull request #10 from tigertext/master

Added ability to include extra data payload into the push packet
Add caveat about passing callbacks using local fun references
Add caveat about passing callbacks using local fun references