Rename variables.scss to _variables.scss

We don't need variables.scss to be compiled into CSS, because it's being imported into app.scss (and get's compiled there). Added an underscore so the Sass compiler ignores this file, which is a common practice with Sass partials (see http://sass-lang.com/guide @ Partials).

resources/assets/sass/_variables.scss

@@ -0,0 +1,37 @@
+
+// Body
+$body-bg: #f5f8fa;
+
+// Borders
+$laravel-border-color: darken($body-bg, 10%);
+$list-group-border: $laravel-border-color;
+$navbar-default-border: $laravel-border-color;
+$panel-default-border: $laravel-border-color;
+$panel-inner-border: $laravel-border-color;
+
+// Brands
+$brand-primary: #3097D1;
+$brand-info: #8eb4cb;
+$brand-success: #2ab27b;
+$brand-warning: #cbb956;
+$brand-danger:  #bf5329;
+
+// Typography
+$font-family-sans-serif: "Raleway", sans-serif;
+$font-size-base: 14px;
+$line-height-base: 1.6;
+$text-color: #636b6f;
+
+// Navbar
+$navbar-default-bg: #fff;
+
+// Buttons
+$btn-default-color: $text-color;
+
+// Inputs
+$input-border: lighten($text-color, 40%);
+$input-border-focus: lighten($brand-primary, 25%);
+$input-color-placeholder: lighten($text-color, 30%);
+
+// Panels
+$panel-default-heading-bg: #fff;