Add Nord color theme (#110)

* Color scheme courtesy of folks at arcticicestudio:
  https://arcticicestudio.github.io/nord/

src/scss/variables.scss

@@ -1,4 +1,6 @@
-$font-family-sans-serif: 'Open Sans','Helvetica Neue',Helvetica,Arial,sans-serif;
+@import 'nord.scss';
+
+$font-family-sans-serif: 'Open Sans','Helvetica Neue',Helvetica,Arial,sans-serif;
 $font-family-monospace: Menlo, Monaco, Consolas, "Courier New", monospace;
 $font-size-base: 14px;
 $font-size-large: 18px;
@@ -129,6 +131,52 @@ $themes: (
         warningColor: $brand-warning,
         logoSuffix: 'white',
     ),
+    nord: (
+        textColor: $nord5,
+        borderColor: $nord2,
+        backgroundColor: $nord2,
+        backgroundColorAlt: $nord1,
+        backgroundColorAlt2: $nord1,
+        scrollbarColor: $nord4,
+        scrollbarHoverColor: $nord5,
+        boxBackgroundColor: $nord2,
+        boxBackgroundHoverColor: $nord3,
+        boxBorderColor: $nord0,
+        headerBackgroundColor: $nord2,
+        headerBorderColor: $nord0,
+        headerInputBackgroundColor: $nord6,
+        headerInputBackgroundFocusColor: $nord5,
+        headerInputColor: $nord2,
+        headerInputPlaceholderColor: $nord3,
+        listItemBackgroundColor: $nord2,
+        listItemBackgroundHoverColor: $nord3,
+        listItemBorderColor: $nord0,
+        groupingsActiveColor: $nord3,
+        disabledIconColor: $nord5,
+        headingColor: $nord4,
+        headingButtonColor: $nord5,
+        headingButtonHoverColor: $nord6,
+        labelColor: $nord4,
+        mutedColor: $nord4,
+        totpStrokeColor: $nord4,
+        boxRowButtonColor: $nord4,
+        boxRowButtonHoverColor: $nord6,
+        inputBorderColor: $nord2,
+        inputBackgroundColor: $nord0,
+        inputPlaceholderColor: $nord4,
+        buttonBackgroundColor: $nord3,
+        buttonBorderColor: $nord0,
+        buttonColor: $nord6,
+        buttonPrimaryColor: $nord9,
+        buttonDangerColor: $nord11,
+        primaryColor: $nord9,
+        primaryAccentColor: $nord8,
+        dangerColor: $nord11,
+        successColor: $nord14,
+        infoColor: $nord9,
+        warningColor: $nord12,
+        logoSuffix: 'white',
+    ),
 );
 
 @mixin themify($themes: $themes) {