Enable bundling of jansson, require 2.11.

CHANGES

UPGRADE-16.txt

configure

configure.ac

include/asterisk/json.h

main/json.c

makeopts.in

third-party/Makefile

third-party/Makefile.rules

third-party/apply_patches

third-party/configure.m4

third-party/jansson/.gitignore

third-party/jansson/Makefile

third-party/jansson/Makefile.rules

third-party/jansson/configure.m4

third-party/jansson/jansson-2.11.tar.bz2.md5

third-party/jansson/patches/0001-Improve-test-coverage.patch

...ansson/patches/0017-Fix-error-handling-in-json_pack.patch

third-party/pjproject/Makefile

third-party/pjproject/Makefile.rules