first changes to improve accesibility, added to textfield for images
alt text
changes to improve accesibility of the web, changes all "i icons" to
"span icons" aded some ids in form inputs, deleted IE check from
base.html, and some others changes
More changes to put more accesible, finished with course teacher zone
last changes to fix last accesibility errors in the site
Merge branch 'master' into accesibility

Conflicts:
	moocng/courses/templates/courses/transcript.html
	moocng/locale/es/LC_MESSAGES/django.mo
	moocng/locale/es/LC_MESSAGES/django.po