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.
I guess I could be misinterpreting @wasade's comment but I think the idea is that you don't have to manually check in python as this is a common thing to do when dropping/creating tables. This should not be a blocker of whether or not this PR gets merged.