Rename command word from 'label' to 'labels'.

'hub issue labels' makes more semantic sense to retrieve all
available labels from the issue tracker. The command 'label'
sounds like the imperative form, i.e. to label an issue.

commands/issue.go

@@ -19,7 +19,7 @@ var (
 		Usage: `
 issue [-a <ASSIGNEE>] [-c <CREATOR>] [-@ <USER>] [-s <STATE>] [-f <FORMAT>] [-M <MILESTONE>] [-l <LABELS>] [-d <DATE>] [-o <SORT_KEY> [-^]] [-L <LIMIT>]
 issue create [-oc] [-m <MESSAGE>|-F <FILE>] [-a <USERS>] [-M <MILESTONE>] [-l <LABELS>]
-issue label
+issue labels
 `,
 		Long: `Manage GitHub issues for the current project.
 
@@ -30,7 +30,7 @@ With no arguments, show a list of open issues.
 	* _create_:
 		Open an issue in the current project.
 
-    * _label_:
+    * _labels_:
         List the labels available in this repository.
 
 ## Options:

commands/label.go

@@ -9,9 +9,9 @@ import (
 
 var (
 	cmdLabel = &Command{
-        Key: "label",
+        Key: "labels",
 		Run: listLabels,
-		Usage: "issue label",
+		Usage: "issue labels",
 		Long: "List the labels available in this repository.",
 	}
 )

features/label.feature

-Feature: hub label
+Feature: hub labels
   Background:
     Given I am in "git://github.com/github/hub.git" git repo
     And I am "testeroni" on github.com with OAuth token "OTOKEN"
@@ -17,7 +17,7 @@ Feature: hub label
       ]
     }
     """
-    When I successfully run `hub issue label`
+    When I successfully run `hub issue labels`
     Then the output should contain exactly:
       """
       bug