acknowledge contributors

[lheagy]

The who page of geosci needs to be improved to be more adequately represent contributors to geosci and promote contribution to open resources in geophysics

Inspiration (please add to this!):

• https://software-carpentry.org/team/
• http://em.geosci.xyz/contributors.html
• ?

cc @jrleeman, @sgkang, @rowanc1, @dougoldenburg