Split up grunt less task

[Hirse]

Split up the grunt less task into common and components following the browserify tasks for the following benefits:

• Clearer structure
• Nicer output
• More granular watching

Output before

Output now

[campersau]

My plan is to get rid of grunt and move stuff like that into a separate ./scripts/* file. Like ./scripts/build.js which does less and browserify.
So I think I am going to skip this PR.
If you want you can start with that instead (I am going to bed shortly) otherwise I will do it tomorrow.

[Hirse]

I understand the plan is to move away from Grunt.
I just wasn't sure how quickly that would happen, so I opened this as a quick follow up from the change in the ESLint PR.

[campersau]

superseded by #1374