pycares-2.2.0

• test: fix CNAME test
• core: parse TTL in PTR replies
• core: parse PTR aliases
• doc: fix installation instructions in README
• doc: fix Channel.set_local_ip documentation
• core: accept local_ip and local_dev as kwargs
• ci, misc: add support for CPython 3.6
• ci: only run CI on master
• ci: disable some Travis notifications
• build: add scripts to build manylinux wheels