BLOCKER: Allow multiple templates per raw data

Multiple fixes in the PR:
- Allows multiple prep templates per raw data
- Preprocessed data is now linked with prep template rather than raw data
- Fixes #326 
- Changes on initialize.sql:
  - SPECTRA removed
  - SFF added
  - FASTA -> FASTA-Sanger

This PR allows @antgonza to continue with his PR.
that is not what I understood. When I said something erroneous, a preprocessed data will not be created, so no need to cascade.