Add display page config info based the config defined in page

@inner
@param {Object} pages the existed display page config
@param {string} sourceDir the project source directory
@param {Object} configFile the config file
function addDisplayPageConfig(pages, sourceDir, configFile) {
    let path = relative(configFile.fullPath, sourceDir);
    let {pageName} = getPageInfo(path);
    let currPageDisplayInfo = pages[pageName];
    let pageConfig = JSON.parse(configFile.content);

    let result = {};
    // filter the illegal not supported config item
    // and map the weixin config name to quick app
    Object.keys(pageConfig).forEach(k => {
        let newKey = DISPLAY_PAGE_CONFIG_MAP[k];
        if (newKey) {
            result[newKey] = pageConfig[k];
        }
    });

    // merge the page config, the config defined in page has higher priority
    // than the app config
    pages[pageName] = Object.assign({}, currPageDisplayInfo, result);
}