Add a priorityColor property to the maniphest conduit endpoint

Summary:
I added a getTaskPriorityColor function to the ManiphestTaskPriority class which returns the color set in the maniphest config for the given priority.

This is in preparation for a change to arcanist which will allow it to display the priority color (if it is a supported color) upon running `arc tasks`.

Fixed some linting issues

Test Plan:
Invoke the maniphest.info method from conduit and ensure that:
 * The priorityColor property is given in the json
 * the priorityColor property is set correctly

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D8734

src/applications/maniphest/conduit/ConduitAPI_maniphest_Method.php

@@ -265,6 +265,8 @@ abstract class ConduitAPI_maniphest_Method extends ConduitAPIMethod {
         'isClosed'     => $task->isClosed(),
         'priority'     => ManiphestTaskPriority::getTaskPriorityName(
           $task->getPriority()),
+        'priorityColor' => ManiphestTaskPriority::getTaskPriorityColor(
+          $task->getPriority()),
         'title'        => $task->getTitle(),
         'description'  => $task->getDescription(),
         'projectPHIDs' => $task->getProjectPHIDs(),

src/applications/maniphest/constants/ManiphestTaskPriority.php

@@ -64,6 +64,17 @@ final class ManiphestTaskPriority extends ManiphestConstants {
     return idx(self::getTaskPriorityMap(), $priority, $priority);
   }
 
+  /**
+   * Retrieve the color of the priority level given
+   *
+   * @param   int     A priority level.
+   * @return  string  The color of the priority if the level is valid,
+   *                  or black if it is not.
+   */
+  public static function getTaskPriorityColor($priority) {
+    return idx(self::getColorMap(), $priority, 'black');
+  }
+
 
   private static function getConfig() {
     $config = PhabricatorEnv::getEnvConfig('maniphest.priorities');