Add callback to force refresh comments

[c3dr0x]

Fix issue #48

Solution

Add two props registerRefreshCommentsMethod and unregisterRefreshCommentsMethod.
They are used to register a method into a parent component to force refresh of components.

Usage

Can be used like followed :

    _refreshComments: undefined,

    registerRefreshCommentsMethod(method) {
        this._refreshComments = method;
    },

    unregisterRefreshCommentsMethod() {
        this._refreshComments = undefined;
    },

    refreshComments() {
        if (this._refreshComments) {
            this._refreshComments();
        }
    },

    [...]

    <FocusComments 
        {...props}
        registerRefreshCommentsMethod={this.registerRefreshCommentsMethod}
        unregisterRefreshCommentsMethod={this.unregisterRefreshCommentsMethod}
    />