Uncaught TypeError: hexToRGB is not a function

This is from a fresh install of Pigments on the latest stable version of Atom. I'm not sure if it's related to this error, but nothing is being colored as well.

### Steps to Reproduce

1. Install atom-pigments
2. Run "Pigments: Reload", or change "Sass Shade And Tint Implementation" setting (to bourbon or compass)

**Atom**: 1.22.1 x64
**Electron**: 1.6.15
**OS**: Ubuntu 16.04.3
**Thrown From**: [pigments](https://github.com/abe33/atom-pigments) package 0.40.2

### Stack Trace

Uncaught TypeError: hexToRGB is not a function

```
At /home/steve/.atom/packages/pigments/lib/color.coffee:163

TypeError: hexToRGB is not a function
at Color.set (/packages/pigments/lib/color.coffee:163:31)
at /packages/pigments/lib/color-expressions.coffee:50:3)
at ColorExpression.module.exports.ColorExpression.parse (/packages/pigments/lib/color-expression.coffee:51:13)
at ColorParser.module.exports.ColorParser.parse (/packages/pigments/lib/color-parser.coffee:11:17)
at ColorContext.module.exports.ColorContext.readColor (/packages/pigments/lib/color-context.coffee:181:22)
at VariablesCollection.module.exports.VariablesCollection.evaluateVariableColor (/packages/pigments/lib/variables-collection.coffee:325:21)
at /packages/pigments/lib/variables-collection.coffee:253:10
at VariablesCollection.module.exports.VariablesCollection.evaluateVariables (/packages/pigments/lib/variables-collection.coffee:267:5)
at /packages/pigments/lib/color-project.coffee:98:18
at Function.module.exports.Emitter.simpleDispatch (/packages/pigments/node_modules/event-kit/lib/emitter.js:25:14)
at Emitter.module.exports.Emitter.emit (/packages/pigments/node_modules/event-kit/lib/emitter.js:141:28)
at /packages/pigments/lib/color-project.coffee:84:41
at /usr/share/atom/resources/app/src/config.js:676:22
at /usr/share/atom/resources/app/src/config.js:693:26
at Function.module.exports.Emitter.simpleDispatch (/usr/share/atom/resources/app/node_modules/event-kit/lib/emitter.js:25:20)
at Emitter.module.exports.Emitter.emit (/usr/share/atom/resources/app/node_modules/event-kit/lib/emitter.js:141:34)
at Config.module.exports.Config.emitChangeEvent (/usr/share/atom/resources/app/src/config.js:884:35)
at Config.module.exports.Config.setRawValue (/usr/share/atom/resources/app/src/config.js:670:25)
at Config.module.exports.Config.set (/usr/share/atom/resources/app/src/config.js:248:20)
at SettingsPanel.set (/usr/share/atom/resources/app/node_modules/settings-view/lib/settings-panel.js:237:27)
at HTMLSelectElement.changeHandler (/usr/share/atom/resources/app/node_modules/settings-view/lib/settings-panel.js:251:24)
```

### Commands

```
2x -8:25.6.0 settings-view:open (input.hidden-input)
3x -6:21.3.0 core:confirm (input.hidden-input)
-5:14.3.0 core:backspace (input.hidden-input)
2x -5:05.6.0 core:save (input.hidden-input)
-4:14 core:move-up (input.hidden-input)
-4:13.1.0 core:move-down (input.hidden-input)
-4:12.9.0 editor:move-to-end-of-screen-line (input.hidden-input)
-3:32.3.0 core:save (input.hidden-input)
-3:02.1.0 editor:delete-to-previous-word-boundary (input.hidden-input)
3x -3:00.8.0 core:save (input.hidden-input)
4x -1:54.4.0 core:backspace (input.hidden-input)
2x -1:53.6.0 editor:delete-to-previous-word-boundary (input.hidden-input)
-0:30.2.0 core:select-all (input.hidden-input)
-0:29.2.0 core:backspace (input.hidden-input)
```

### Non-Core Packages

```
atom-beautify 0.30.5
language-gitignore 0.3.0
language-haml 0.25.2
language-pug 0.0.21
language-vue 0.23.1
language-vue-component 0.5.0
markdown-preview-plus 2.4.16
minimap 4.29.7
pigments 0.40.2
pure-syntax 0.3.0
```