Conditionally show GEMINI button on slice page.
Conditionally show GEMINI button on slice page.

If the user has the 'gemini-user' attribute, show the
button. Otherwise, hide it.

tcmitchell/geni-portal,charliemeyer/geni-portal,charliemeyer/geni-portal,charliemeyer/geni-portal,tcmitchell/geni-portal,tcmitchell/geni-portal,charliemeyer/geni-portal,tcmitchell/geni-portal,charliemeyer/geni-portal,tcmitchell/geni-portal