Add spec for loading theme with incomplete variable file
Add cssForFile to LessCompileCache
Load packages with the fallback variables
Load fallback variables in the user’s stylesheet
import the fallback variables in the base theme
Use less-cache@0.13.0
Upgrade to tabs to fix tab size issue
Don’t need the absolute path, just `variables` 

`static` is already on the path
Upgrade to apm 0.78
Merge pull request #2941 from atom/bo-fallback-vars

Import base *-variables files as fallback vars when loading packages/themes
Upgrade to language-c@0.22