Express Middleware - header settings

Express middleware for setting header, for centralizing settings between services.

Sets the following:

• res.header("Access-Control-Allow-Origin", options.origin);
• res.header("Access-Control-Allow-Methods", options.methods);
• res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Authorization, appname, Accept, responseType, referer, Accept-Encoding, Content-Encoding" + options.headers);
• res.header("Access-Control-Expose-Headers", options.headers);

defaults:

• origin: "*"
• methods: "PUT,GET,POST,DELETE,OPTIONS"
• allow-headers: "Origin, X-Requested-With, Content-Type, Authorization, appname, Accept, responseType, referer, Accept-Encoding, Content-Encoding"

options:

• origin: Array of strings of origins
• methods: Array of strings of methods
• headers: Array of strings of custom headers