Local gotham

Switch Dashboard to use local versions of Gotham fonts.
````
 egrep -r '%b\W' app | grep 'haml:'
app/views/callouts/show.html.haml:  %b Element:
app/views/callouts/show.html.haml:  %b Text:
app/views/level_source_hints/show_pop_hints.html.haml:      %b= LevelSourceHint::USER_VISIBLE_NAMES["#{@restriction}"]
app/views/levels/_match.html.haml:              %b X
app/views/levels/_multi.html.haml:      %b.multi-question!= data['questions'][0]['text']
app/views/levels/_multi.html.haml:              %b X
app/views/reports/admin_stats.html.haml:%b Total users
app/views/reports/admin_stats.html.haml:%b Students
app/views/reports/admin_stats.html.haml:%b Teachers
app/views/reports/admin_stats.html.haml:%b Gender (when specified):
app/views/reports/admin_stats.html.haml:%b Users linked to a teacher
app/views/reports/admin_stats.html.haml:%b Users with an email address
app/views/reports/admin_stats.html.haml:%b Teachers with a confirmed email address
app/views/reports/admin_stats.html.haml:%b Total student prizes earned
app/views/reports/admin_stats.html.haml:%b Total student prizes redeemed
app/views/reports/admin_stats.html.haml:%b Student prizes available to be redeemed
app/views/reports/admin_stats.html.haml:%b Total teacher prizes earned
app/views/reports/admin_stats.html.haml:%b Total teacher prizes redeemed
app/views/reports/admin_stats.html.haml:%b Teacher prizes available to be redeemed
app/views/reports/admin_stats.html.haml:%b Total bonus teacher prizes earned
app/views/reports/admin_stats.html.haml:%b Total teacher bonus prizes redeemed
app/views/reports/admin_stats.html.haml:%b Teacher bonus prizes available to be redeemed
app/views/reports/prizes.html.haml:      %b DonorsChoose.org rewards are no longer available as of June 15, 2014. Please refer to this
app/views/reports/prizes.html.haml:      %b= link_to 'FAQ', 'https://support.code.org/hc/en-us/articles/202446516'
app/views/reports/prizes.html.haml:      %b for more information.
app/views/reports/prizes.html.haml:      %b= link_to 'FAQ', 'https://support.code.org/hc/en-us/articles/202446516'
app/views/reports/prizes.html.haml:      %b for more information.
app/views/shared/_redeemed_prize.html.haml:  %b= t('redeem_prizes.provider')
app/views/shared/_redeemed_prize.html.haml:  %b= t('redeem_prizes.code')
app/views/videos/test.html.haml:    %b from a student computer
````