Add other code sites with issue tracking

[jdungan]

To add sites other than github to the addon these files have to change

• manifest.json

    "permissions": [
        "https://*.codesy.io/",
        "*://codesy-stage.herokuapp.com/",
        "*://*.github.com/*",
        "storage",
        "tabs",
        "webRequest",
        "webRequestBlocking"
    ],
    "content_scripts": [
        {
            "all_frames": false,
            "js": [
                "js/jquery-3.2.0.min.js",
                "js/issue.js"
            ],
            "matches": [
                "*://*.github.com/*"
            ]
        },

• csp.js:

const githubFilter = {
    urls: ["*://*.github.com/*"],
    types: ["main_frame"]
};

• issue.js:

    const issue_rx = /https:\/\/github.com\/.*\/issues\/[1-9]+/

• on_install.js

function when_installed ({reason}) {
    find_these({ title: "*codesy.io*" })
            .then(select_them)
                .then(reload_them)
                    .then(()=>{
                        find_these({ url: "*://*.github.com/*" })
                            .then(reload_them)
                    })
}