fix: resolve #265 - custom token named token breaks subsequent tokens

[abhii734]

Bug (morgan#265)

Adding a token named "token" causes all subsequent tokens to break. This is because morgan.token() overwrites the morgan.token function itself.

Fix

• Store custom tokens in separate tokenStore object
• Prevent overwriting built-in properties (token, format, compile)
• Add morgan.getToken() method for compiled format functions to lookup tokens
• Also add NO_COLOR support in dev format (morgan#302)

Verification

Test code that previously failed:

var logger = require("morgan");
logger.token("ip", function (req, res) { return req.ip ? req.ip : "" });
logger.token("token", function (req, res) { return (req.token ? req.token.token : "") });
logger.token("uuid", function (req, res) { return (req.token ? req.token.uuid : "") });

This now works without "TypeError: tokens.uuid is not a function"