Closes #55. Allows you to set the primary color.

This certainly should not be seen as the final implementation of this.
I imagine that requests like this will happen for many other colors in
the system, it might be good at some point to allow them to upload their
own stylesheet to be used.

app/Http/Controllers/SettingController.php

@@ -38,6 +38,9 @@ class SettingController extends Controller
         foreach($request->all() as $name => $value) {
             if(strpos($name, 'setting-') !== 0) continue;
             $key = str_replace('setting-', '', trim($name));
+            if($key == 'app-color') {
+                Setting::put('app-color-rgba', $this->hex2rgba($value, 0.15));
+            }
             Setting::put($key, $value);
         }
 
@@ -45,4 +48,51 @@ class SettingController extends Controller
         return redirect('/settings');
     }
 
+    /**
+     * Adapted from http://mekshq.com/how-to-convert-hexadecimal-color-code-to-rgb-or-rgba-using-php/
+     * Converts a hex color code in to an RGBA string.
+     *
+     * @param string $color
+     * @param float|boolean $opacity
+     * @return boolean|string
+     */
+    protected function hex2rgba($color, $opacity = false)
+    {
+        // Return false if no color provided
+        if(empty($color)) {
+            return false;
+        }
+        // Trim any whitespace
+        $color = trim($color);
+
+        // Sanitize $color if "#" is provided
+        if($color[0] == '#' ) {
+            $color = substr($color, 1);
+        }
+
+        // Check if color has 6 or 3 characters and get values
+        if(strlen($color) == 6) {
+            $hex = array( $color[0] . $color[1], $color[2] . $color[3], $color[4] . $color[5] );
+        } elseif( strlen( $color ) == 3 ) {
+            $hex = array( $color[0] . $color[0], $color[1] . $color[1], $color[2] . $color[2] );
+        } else {
+            return false;
+        }
+
+        // Convert hexadec to rgb
+        $rgb =  array_map('hexdec', $hex);
+
+        // Check if opacity is set(rgba or rgb)
+        if($opacity) {
+            if(abs($opacity) > 1)
+                $opacity = 1.0;
+            $output = 'rgba('.implode(",",$rgb).','.$opacity.')';
+        } else {
+            $output = 'rgb('.implode(",",$rgb).')';
+        }
+
+        // Return rgb(a) color string
+        return $output;
+    }
+
 }