Updated help output to prefer true/false to yes/no

Similarly, I updated the API Reference too:
https://github.com/ariya/phantomjs/wiki/API-Reference/7cddd19676a917535b74d386c3974da00fbbe793

This arguably makes more sense to PhantomJS's typical audience of web developers.

Discussed this with @detro earlier, too:
> **me:** Is using 'yes'/'no' on the command line that much more typical than 'true'/'false'?
> **Ivan:** typical?
> well, we give the option to choose
> they both work
> **me:** like in other applications run from the command line
> Our code handles both... but I feel like, given our audience, 'true'/'false' might be better choice (i.e. for the docs)
> **Ivan:** I see what you mean
> **Ivan:** well, I personally prefer true/false
> **Ivan:** and probably Ariya too
> **me:** But to a web developer, 'yes'/'no' is less natural than 'true'/'false'
> **me:** Also, if you were generating it from code, you have to code for that translation rather just converting your boolean to a string
> **Ivan:** good point

Also includes my changes for PR #387, which hopefully makes it easier to merge...?