Merge branch 'improve_more_buttons' into 'master'

Improve admin area button style

A lot of the buttons in the top right in the admin area were too big. This makes those the new `btn-nr` size which seems to look nice.

## User buttons

### Current

![Screen_Shot_2016-01-08_at_2.29.30_PM](/uploads/8920d4a67ff4a20617e5b4d319ba154e/Screen_Shot_2016-01-08_at_2.29.30_PM.png)

### New

![Screen_Shot_2016-01-08_at_2.29.21_PM](/uploads/494741f6e92592ff2c60683f399bb1c1/Screen_Shot_2016-01-08_at_2.29.21_PM.png)

## Project edit button

### Current

![Screen_Shot_2016-01-08_at_2.29.59_PM](/uploads/09a2f8fddc45120510dd10758ce33c51/Screen_Shot_2016-01-08_at_2.29.59_PM.png)

### New ![Screen_Shot_2016-01-08_at_2.30.14_PM](/uploads/93a72a7c42b1974643b1e9ffd3ec8511/Screen_Shot_2016-01-08_at_2.30.14_PM.png)

## Label button

### Current

![Screen_Shot_2016-01-08_at_2.38.09_PM](/uploads/9cff790e1a4e2d650487c9765d0235a4/Screen_Shot_2016-01-08_at_2.38.09_PM.png)

### New

![Screen_Shot_2016-01-08_at_2.38.31_PM](/uploads/9462ff2393249eb762dc7cb92605c733/Screen_Shot_2016-01-08_at_2.38.31_PM.png)

cc/ @jschatz1 @creamzy @skyruler 

See merge request !2351

app/views/admin/labels/index.html.haml

 - page_title "Labels"
-= link_to new_admin_label_path, class: "pull-right btn btn-new" do
+= link_to new_admin_label_path, class: "pull-right btn btn-nr btn-new" do
   New label
 %h3.page-title
   Labels

app/views/admin/projects/show.html.haml

 - page_title @project.name_with_namespace, "Projects"
 %h3.page-title
   Project: #{@project.name_with_namespace}
-  = link_to edit_project_path(@project), class: "btn pull-right" do
+  = link_to edit_project_path(@project), class: "btn btn-nr pull-right" do
     %i.fa.fa-pencil-square-o
     Edit
 %hr

app/views/admin/users/_head.html.haml

@@ -7,8 +7,8 @@
 
   .pull-right
     - unless @user == current_user || @user.blocked?
-      = link_to 'Impersonate', impersonate_admin_user_path(@user), method: :post, class: "btn btn-grouped btn-info"
-    = link_to edit_admin_user_path(@user), class: "btn btn-grouped" do
+      = link_to 'Impersonate', impersonate_admin_user_path(@user), method: :post, class: "btn btn-nr btn-grouped btn-info"
+    = link_to edit_admin_user_path(@user), class: "btn btn-nr btn-grouped" do
       %i.fa.fa-pencil-square-o
       Edit
 %hr