User metrics & other enhancements (v8.8)

Main changed files: www\index.html, gateway.js, metrics.js, package.json, removed gateway_NeDB-2-Binary.js, added userMetrics\README.md, added userMetrics_example.js

IMPORTANT NEW REQUIREMENT: merge nodejs package (get latest packages.json and run npm update in your gateway directory to install it). This is required for the main new feature (user metrics)

• user metrics folder, allows you to move your own custom metrics in a place where they don't mingle with the defaults in metrics.js, you can also override/change the existing defaults or add new ones, see README in userMetrics folder for details. You can customize a default metric by copying it from metrics.js, beautify it with jsBeautifier then paste it in your own userMetrics/yourNewMetric.js file. For changes to take effect the app needs to be restarted at this point. Here's how to use jsBeautifier:
  
• updated nedb to 1.8, json5 to 0.5, request to 2.75, console-stamp to 0.2.4
• removed old neDB upgrade script (gateway_NeDB-2-Binary.js)
• (total log disk space / visible data disk space) in graph status:
  
• server uptime on terminal page:
  
• added support for flot curvedLines. Please note this will result in many interpolation points injected in the graph by this plugin, these are not part of the original logged data and the graph stat will still reflect the number of points used to generate the visible graph. The userMetrics/_example.js "H" metric illustrates how to use it. Graph results in a smoother curve rather than stepped values: