Update /courses fwd/back links to be more consistent

Teachers, click here! is bit bigger.

app/styles/courses/courses-view.sass

@@ -1,5 +1,5 @@
 #courses-view
-  #site-content-area
+  #main-content
     padding-left: 250px
     padding-right: 250px
 

app/templates/courses/course-details.jade

@@ -2,12 +2,12 @@ extends /templates/base
 
 block content
 
-  h2
   if view.teacherMode
     a(href="/courses/teachers") Back to my classrooms
   else
     a(href="/courses") Back to my courses
-  hr
+  br
+  br
 
   if (noCourseInstance || noCourseInstanceSelected) && course
     h1= course.get('name')

app/templates/courses/courses-view.jade

@@ -1,12 +1,11 @@
 extends /templates/base
 
 block content
-  .pull-right
+  h3.text-right
     if me.isAnonymous()
       a(href="/teachers") Teachers, click here!
     else
       a(href="/courses/teachers") Teachers, click here!
-  br
 
   #main-content
     if me.isAnonymous()