Remove spurious scss-lint configuration

It was broken due to several reasons:

* Bad globs from not catching up after file renames.
* Bad rule indentation.

Also, the scss-lint project itself recommends using other tools, because
it relies on the ruby SASS implementation while upstream has moved to a
dart-based implementation.

Even when you fix the config and try to run the tool, you feel the pain
of this deviation:

```
$ scss-lint
(...)

app/webpacker/css/admin/grid.scss:10:1 [E] Syntax: Syntax Error: Invalid CSS after "$col-width: math": expected selector or at-rule, was ".div($total-col..."

(...)
```

The grid.scss file use using `math.div` feature, which is only supported
by the `sass` version based on dart. `scss-lint` will never be able to
parse this file at all.

Also, we're already handling scss rule formatting through prettier.

Because of all these reasons, it's best to forget about scss-lint.

.codeclimate.yml

@@ -5,23 +5,6 @@ plugins:
     channel: "rubocop-1-12"
     config:
       file: ".rubocop.yml"
-  scss-lint:
-    enabled: true
-    checks:
-      ImportantRule:
-        enabled: false
-      VendorPrefix:
-        enabled: false
-      LeadingZero:
-        enabled: false
-      PropertySortOrder:
-        enabled: false
-      StringQuotes:
-        enabled: false
-      DeclarationOrder:
-        enabled: false
-      NestingDepth:
-        enabled: false
 
   duplication:
     enabled: true

.hound.yml

@@ -1,4 +1,2 @@
 rubocop:
   config_file: .rubocop_styleguide.yml
-scss:
-  config_file: .scss-lint.yml

.scss-lint.yml

@@ -1,19 +0,0 @@
-scss_files: 'app/assets/stylesheets/**/*.css.scss'
-
-exclude: 'app/assets/stylesheets/shared/**'
-
-linters:
-  ImportantRule:
-    enabled: false
-    VendorPrefix:
-      enabled: false
-    LeadingZero:
-      enabled: false
-    PropertySortOrder:
-      enabled: false
-    StringQuotes:
-      enabled: false
-    DeclarationOrder:
-      enabled: false
-    NestingDepth:
-      enabled: false