Configuration

[jeddeloh]

This is just a proposal, but there are three things I would love to be able to do:

• Configure the type for context across the library (see this comment)
• Use reason-promise or another library by default, but allow people to opt out or provide their own promise transformation function
• Allow people to customize the behavior of parse. Right now it throws an exception, but maybe you'd like do something else—return a variant, log before throwing, etc.

Right now, turning all the file modules into functors seems like the only way to achieve this, but it's probably worth thinking about more.

[jeddeloh]

v1.0.0 contains what I considered to be the best tradeoff for me given the current forces and personal bandwidth, so I'm calling this done. I would encourage anyone who wants to take another pass at configuration to dive in and give it a go. It would be really awesome!