[#350] btn add new member is now more clear

tracim/tracim/public/assets/css/dashboard.css

   color: #31708f;
 }
 .content__home__tab__content-unread {
-    float: right;
+  float: right;
   margin-bottom: 15px;
 }
 

tracim/tracim/templates/admin/workspace_getone.mak

         % if potential_new_user_nb<=0:
             ${TITLE.H3(_('Members'), 'fa-user', 'workspace-members')}
         % else:
-            ${TITLE.H3_WITH_BUTTON(fake_api.current_user, result.workspace, 'workspace-members', _('Members'), 'add-role-from-existing-user-form', _('add one...'), 'fa-user')}
+            ${TITLE.H3_WITH_BUTTON(fake_api.current_user, result.workspace, 'workspace-members', _('Members'), 'add-role-from-existing-user-form', _('add one...'), 'fa-user', 'btn btn-link')}
 
             <div id="add-role-from-existing-user-form" class="collapse col-sm-9">
                 <div class="pod-inline-form">

tracim/tracim/templates/widgets/title.mak

         ${label}
     </h3>
 </%def>
-<%def name="H3_WITH_BUTTON(current_user, workspace, dom_id, label, action_dom_id='', action_label='', fa_icon='')">
+<%def name="H3_WITH_BUTTON(current_user, workspace, dom_id, label, action_dom_id='', action_label='', fa_icon='', custom_classes='')">
     <h3 id="${dom_id}">
         ${ICON.FA('t-less-visible '+fa_icon) if fa_icon else ''}
         ${label}
         ## Button is shown for contributors (or more), not for readers
         % if h.user_role(current_user, workspace)>1:
             % if action_dom_id and action_label:
-                <small class="t-spacer-left">${BUTTON.DATA_TARGET_AS_TEXT(action_dom_id, action_label)}</small>
+                <small class="t-spacer-left">${BUTTON.DATA_TARGET_AS_TEXT(action_dom_id, action_label, custom_classes)}</small>
             % endif
         % endif
     </h3>