Improve v2

[tarampampam]

Q	A
Bug fix?	Yes
New feature?	Yes

Description

Added

• Middleware SetServerPortMiddleware for automatic setting SERVER_PORT in server parameters bag if it does not set before (value based on request schema; this middleware fixes empty port value like https://127.0.0.1:/ when exposed default port without set SERVER_PORT)
• Environment variable RR_WORKER_CLASS supports for overriding default worker class (watch in ./bin/rr-worker)
• Docker-based environment for development
• Project Makefile

Changed

• Allowed RR configuration options (http.fcgi.*, http.http2.*, headers.*) (do not forget update your existing config files)
• Minimal Laravel version now is 5.5.x
• Minimal spiral/roadrunner version now is ^1.4.6
• Composer scripts
• Package service-provider automatically register SetServerPortMiddleware middleware
• Constant RULE_METHOD_PREFIX in CallbacksInitializer class now protected
• Constants BOOL_OPTION_INVERT_LOGIC_NAME_PREFIX and OPTIONS_PREFIX in StartOptions class now protected
• Method start() must returns void in WorkerInterface interface

Removed

• Dev-dependency avto-dev/dev-tools

Checklist

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I wrote unit tests for my code
• [x] I have made changes in CHANGELOG.md file

About your changes in CHANGELOG.md:

• Add new version header like ## v1.x.x, if it does not exists
• Add description under Added / Changed / Fixed sections
• Add reference to closed issues [#000]
• Add link to issue in the end of document