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 though the agreement was that if it had been submitted to EBI then you
would not be able to delete it but if you generated something that was
ultimately erroneous it would be fine to remove it.

On (Oct-29-14|16:56), josenavas wrote:
> > +            If the prep template already has a preprocessed data
> > +        QiitaDBUnknownIDError
> > +            If no prep template with id = id_ exists
> > +        """
> > +        table_name = cls._table_name(id_)
> > +        conn_handler = SQLConnectionHandler()
> > +
> > +        if not cls.exists(id_):
> > +            raise QiitaDBUnknownIDError(id_, cls.__name__)
> > +
> > +        preprocessed_data_exists = conn_handler.execute_fetchone(
> > +            "SELECT EXISTS(SELECT * FROM qiita.prep_template_preprocessed_data"
> > +            " WHERE prep_template_id=%s)", (id_,))[0]
> > +
> > +        if preprocessed_data_exists:
> > +            raise QiitaDBError("Cannot remove prep template %d because a "
> 
> On the discussion that we had on tuesday we said that we are going to allow the deletion if and only if a preprocessed data has not been generated (it can potentially already be submitted to EBI).
> 
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