Updated F2.log API

We've updated the `F2.log` API to support [all the console methods](https://developers.google.com/chrome-developer-tools/docs/console-api) (clear, error, group, info, warn, etc) in addition to providing better handling of logged messages. 

Previously, `F2.log(arg)` would output an `array` of values and often those values would get truncated or abbreviated in the console. The new `F2.log` will pass arguments directly to `console.log` (or whichever console method you provide, such as `console.warn`). 

Usage is easy:

`F2.log(args)` => `console.log(args)`
`F2.log(methodName, args)` => `console[methodName](args)` example `F2.log('warn', args)`

See [more in ../src/F2.js](https://github.com/OpenF2/F2/blob/log_API/sdk/src/F2.js#L276).

This is short-term fix for truncated messages while we look closer at #91.