Improve screen reader user experience on logistration page

Description

*Description*
This is a follow-up to #8603, addressing @cptvitamin's [feedback to improve the experience of screen reader users on the logistration page](https://github.com/edx/edx-platform/pull/8603#issuecomment-115828851).

*Merge Target*: Cypress release

*Screenshot*: Looks visually identical to #8603

*Sandbox*: http://sandbox4.opencraft.com/login

*Reviewers*:
@Kelketek and @cptvitamin

Done

Assignee

Mark Sadecki

Reporter

Edx Admin [Administrator]

Labels

Contributor Name

Braden MacDonald

Repo

edx/edx-platform

Customer

Epic Link

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OSCM Assignee

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Platform Map Area (Levels 3 & 4)

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Blended Hour Utilization Percentage

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edX Theme

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edX Squad

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Github Lines Deleted

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Priority

Unset