change outcomes index headings to be sequential from h1

fixes CNVS-13123

test plan:
- go to the course outcomes page
- enable a screenreader and view the headings list
- it should now have sequential headings, starting at h1 (specifically for this
  page, it should have an h1 and an h2)

Change-Id: I616d212c343df7b8e277b505aa00e93697ddda7b
Reviewed-on: https://gerrit.instructure.com/38255
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Anna Koalenz <akoalenz@instructure.com>
Reviewed-by: Cameron Sutter <csutter@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>

app/views/jst/outcomes/findInstructions.handlebars

@@ -1,9 +1,9 @@
 <div class="wrapper">
-  <h3 class="title">
+  <h2 class="title">
     {{#t "instructions.find.title"}}
     Finding Outcomes
     {{/t}}
-  </h3>
+  </h2>
   <div class="description">
     {{#t "instructions.find.description"}}
     <p>Outcomes created by your institution, or state can be accessed here. Just like in your course, the panel to the left will allow you to navigate between existing outcomes. Once you have found the outcome or outcome group you wish to use, click the import button below to add it to your course.</p>

app/views/jst/outcomes/mainInstructions.handlebars

@@ -1,9 +1,9 @@
 <div class="wrapper">
-  <h3 class="title">
+  <h2 class="title">
     {{#t "instructions.main.manage.title"}}
     Setting up Outcomes
     {{/t}}
-  </h3>
+  </h2>
   <div class="description">
     {{#t "instructions.main.manage.description"}}
     <p>Outcomes are created here to track mastery in a course.  To get started, checkout the menu bar along the top. Click on the New button to create a new outcome, or the New Group button to create a new group to organize your outcomes into. The Find button will allow you to use outcomes that have been created by your state or institution. As you create and use outcomes you will be able to use the panel to the left to navigate through your outcomes. You can drag and drop outcomes between the different levels to create structure.</p>

app/views/jst/outcomes/outcome.handlebars

@@ -1,11 +1,11 @@
-<h3 class="title">
+<h2 class="title">
   <i class="icon-note-light"></i>
   {{#unless isLargeRoster}}
     <a href='{{html_url}}'>{{title}}</a>
   {{else}}
     {{title}}
   {{/unless}}
-</h3>
+</h2>
 <div class="description">
   {{{description}}}
 </div>

app/views/jst/outcomes/outcomeGroup.handlebars

@@ -1,7 +1,7 @@
-<h3 class="title">
+<h2 class="title">
   <i class="icon-folder"></i>
   {{title}}
-</h3>
+</h2>
 <div class="description">
   {{{description}}}
 </div>

app/views/outcomes/index.html.erb

@@ -4,6 +4,6 @@
   content_for :page_title, t("#titles.learning_outcomes", "Learning Outcomes")
 %>
 
-<h2><%= t("#titles.learning_outcomes", "Learning Outcomes") %></h2>
+<h1><%= t("#titles.learning_outcomes", "Learning Outcomes") %></h1>
 
 <div id="outcomes"></div>