First installment of updates for filebench workloads.

Goal: update filebench workload files to reflect changes in the WML.
Two additional changes:
- Version numbers from now on reflect the last filebench release
  that changed the workload file. Thus, all versions are now set
  to 1.5
- Workload files now end in .fb to avoid being interpreted by tools
  as Fortran source. An .fb file now combines the functionality in
  the old .f and .prof files