Adding information about the Software Carpentry Foundation.

1.  Created `scf` directory to hold documents.
2.  Wrote `scf/index.html` with links to documents.
3.  Modified navigation bar to link to this (padding is off).
4.  Modified Makefile to rebuild when SCF material changes.
Peter Steinbach
Cleaning up nav bar
Merge branch 'master' into adding-scf-material
Adding committee roles and responsibilities
Fixing formatting of executive director page
Merge branch 'adding'
Merge branch 'adding-scf-material'