Cleanup groups pages UI a bit

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/generic/common.scss

@@ -379,7 +379,7 @@ table {
   list-style: none;
   text-align: center;
   padding-bottom: 15px;
-  margin-bottom: 10px;
+  margin-bottom: 15px;
 
   li {
     display: inline-block;

app/views/dashboard/groups/index.html.haml

 - page_title "Groups"
 = render 'dashboard/groups_head'
 
-%h3.page-title
-  Group Membership
+.slead
+  Group members have access to all group projects.
   - if current_user.can_create_group?
     %span.pull-right.hidden-xs
-      = link_to new_group_path, class: "btn btn-new" do
+      = link_to new_group_path, class: "btn btn-new btn-sm" do
         %i.fa.fa-plus
         New Group
-%p.light
-  Group members have access to all group projects.
-%hr
 .panel.panel-default
   .panel-heading
     %strong Groups

app/views/explore/groups/index.html.haml

 - page_title "Groups"
 - if current_user
   = render 'dashboard/groups_head'
-.clearfix
+.clearfix.append-bottom-10
   .pull-left
     = form_tag explore_groups_path, method: :get, class: 'form-inline form-tiny' do |f|
       = hidden_field_tag :sort, @sort
@@ -30,15 +30,12 @@
           = link_to explore_groups_path(sort: sort_value_oldest_updated) do
             = sort_title_oldest_updated
 
-%hr
-
 %ul.bordered-list
   - @groups.each do |group|
     %li
       .clearfix
         %h4
           = link_to group_path(id: group.path) do
-            %i.fa.fa-users
             = group.name
       .clearfix
         %p