Update help for welcome, register, and login pages

All now go to getting started, but have different tokens, for further
segmenting later.

cms/templates/howitworks.html

 <%inherit file="base.html" />
+<%def name="online_help_token()"><% return "welcome" %></%def>
 <%namespace name='static' file='static_content.html'/>
 <%!
   from django.core.urlresolvers import reverse

cms/templates/login.html

 <%inherit file="base.html" />
+<%def name="online_help_token()"><% return "login" %></%def>
 <%!
 from django.core.urlresolvers import reverse
 from django.utils.translation import ugettext as _

cms/templates/register.html

 <%! from django.utils.translation import ugettext as _ %>
 <%inherit file="base.html" />
+<%def name="online_help_token()"><% return "register" %></%def>
 <%! from django.core.urlresolvers import reverse %>
 
 <%block name="title">${_("Sign Up")}</%block>

cms/templates/widgets/header.html

@@ -150,11 +150,8 @@
       <nav class="nav-not-signedin nav-pitch">
         <h2 class="sr">${_("You're not currently signed in")}</h2>
         <ol>
-          <li class="nav-item nav-not-signedin-hiw">
-            <a href="/">${_("How Studio Works")}</a>
-          </li>
           <li class="nav-item nav-not-signedin-help">
-            <a href="http://help.edge.edx.org/" rel="external">${_("Studio Help")}</a>
+            <a href="${get_online_help_info(online_help_token)['doc_url']}" title="${_("Contextual Online Help")}" target="${_("_blank")}">${_("Help")}</a>
           </li>
           <li class="nav-item nav-not-signedin-signup">
             <a class="action action-signup" href="${reverse('signup')}">${_("Sign Up")}</a>

docs/config.ini

@@ -30,6 +30,9 @@ advanced = index.html
 checklist = building_course/creating_new_course.html#use-the-course-checklist
 import = building_course/export_import_course.html#import-a-course
 export = building_course/export_import_course.html#export-a-course
+welcome = getting_started/get_started.html
+login = getting_started/get_started.html
+register = getting_started/get_started.html
 
 # below are the language directory names for the different locales
 [locales]