ACTION-296: Add labels to form controls

From Kevin White:

Login form has no labels for the form elements. There is a placeholder which is insufficient. This is evident on other forms throughout the site, such as the Live Search text entry field and the chair check boxes on the group participants listing page. There are instances where there are form labels that are not correctly associated with the form element. For example, on the Propose a Community Group (http://cgbeta.w3.org/community/groups/propose_cg/) there are form labels but the form elements do not have ID attributes that allow for the label to be correctly associated. When leaving a comment, the comment box has a correctly associated label. Unfortunately, it is styled with display: none. This means that it is generally not read out by screen readers, so unavailable to these users.
Suggestion: For each form element, add a correctly associated label. This can be moved off screen to avoid impacting on the visual design. Don’t use ‘display: none’ to hide the label. Alternatively a title attribute could be used.

Left-align the labels with the margin.
Left align the input controls with themselves.