Add Nord color scheme

The color scheme (1) supports all global settings (2) and base scopes (3)
according to the "Nord Style Guideslines" (4).

> Package Support

>> Languages

* Babel (5) (babel-sublime)
  * Decorators
  * Strings (Interpolated & Template Expressions + Keywords)
  * Constants
  * Object Keys & Variables
  * Arrow Functions
  * Static Variables
  * Classes
  * Spread Operators
  * Exports
* TypeScript (6)
  * Inherited Classes
  * Classes & Enums
  * Types
  * Primitives
  * Decorators
  * Strings (Interpolated & Template Expressions + Keywords)
  * Static Support Functions
  * Constants
  * JSDoc Tags

>> UI

* SublimeLinter (7)
  * Warnings
  * Errors
  * Gutter Marks
  * Ignored
  * Untracked
  * Inserted
  * Changed
  * Deleted
* GitGutter (8)
  * Ignored
  * Untracked
  * Inserted
  * Changed
  * Deleted

References:
  (1) https://www.sublimetext.com/docs/3/color_schemes.html
  (2) https://www.sublimetext.com/docs/3/color_schemes.html#global_settings
  (3) https://www.sublimetext.com/docs/3/scope_naming.html
  (4) https://github.com/arcticicestudio/nord
  (5) https://packagecontrol.io/packages/Babel
  (6) https://packagecontrol.io/packages/TypeScript
  (7) https://packagecontrol.io/packages/SublimeLinter
  (8) https://packagecontrol.io/packages/GitGutter

GH-1

Nord.skins

@@ -0,0 +1,7 @@
+{
+  "Nord": {
+    "Preferences": {
+      "color_scheme": "Packages/nord-sublime-text/Nord.tmTheme"
+    }
+  }
+}