Adds "core team" section to OpenReferral CfA page

- Adds core team section to OpenReferral CfA page.
- Adds photos of missing team members to CfA media directory.
- Hyphenates filenames for people to be consistent with other people’s
images.
Merge pull request #549 from anselmbradford/add-or-team

Adds "core team" section to OpenReferral CfA page