Add "Preferences" tab to account page

[eaquigley]

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Author Name: Xiangqing Yang (@xyang02)
Original Redmine Issue: 3516, https://redmine.hmdc.harvard.edu/issues/3516
Original Date: 2014-02-03
Original Assignee: Xiangqing Yang

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Add "Preferences" tab to account page to display user preferences.

[eaquigley]

@mheppler do you remember what this tab was supposed to be? i am drawing a blank.