Update dependency fourseven:scss

[raym]

Fixes #10606 by updating the version of fourseven:scss implied in package.js.

Also fixed a syntax error that was throwing an error when including this into a meteor project:

=> Started proxy.                             
=> Errors prevented startup:                  
   
   While processing files with ecmascript (for target web.browser):
   <anonymous>: .babelrc is not a valid JSON file: Unexpected token ] in JSON at position 356
   at JSON.parse (<anonymous>)
   at BabelCompiler.BCp._inferFromBabelRc (packages/babel-compiler.js:255:16)
   at BabelCompiler.BCp.inferExtraBabelOptions (packages/babel-compiler.js:244:10)
   at BabelCompiler.BCp.processOneFileForTarget (packages/babel-compiler.js:174:10)
   at BabelCompiler.<anonymous> (packages/babel-compiler.js:111:26)
   at Array.forEach (<anonymous>)
   at BabelCompiler.BCp.processFilesForTarget (packages/babel-compiler.js:110:14)

I also noted that Node 8 was required to get this running properly, which I was unaware of but is probably common knowledge.

[ncoden]

Thank you @raym

[ncoden]

Actually, this introduced an issue: Foundation is considered as compatible anymore with older Meteor versions (but it should be).

I think we can use the following version range instead:

fourseven:scss@3.4.1 || 4.0.0

I lost a lot of time searching for this "version range" thing in Meteor so I hope this will works. The Atmosphere ecosystem has serious issues with compatibility management compared to npm.