Use new factory definition syntax

[paulcsmith]

Pros

• Can use symbol view/ctags to jump to the factories more easily
• Can add helper functions underneath the factory they belong to
• IMO it's easier to scan your factory module for a particular factory
• Easier to type :)
• If/when callbacks are introduced, this will allow you to put the
  callback functions near the factory

Cons

• A little more magic since you still call the functions with atoms,
  e.g.build(:user)

Closes #101

[jsteiner]

I'm down with this, mainly for defining helper functions and callbacks near the function.

I'm not sure how often ctags would be useful since it would be rare to use the function directly.

[paulcsmith]

Good point. Ctags are probably useless here, but a lot of editors have "Jump to Definition/Symbol Views" where you can jump to a function. Right now they're all called factory so this should make it easier for people using those editors (I hope :D)

I'll go ahead and merge this in. Thanks for the review!

[quolpr]

The regex that can help you to migrate to new factory version:
Replace def factory\(:(.*?)\) with def $1_factory

Can be done in atom/vscode