BUG: Use ontology terms for EBI investigation_type

Use the terms stored in the database and add a new argument, `new_investigation_type`, which is only relevant if the value passed in `investigation_type` is `Other`.

See issue #405.

NOT READY FOR MERGE - I couldn't run the tests in my system.
What do you mean not_ontology?

On (Nov-10-14|19:58), Antonio Gonzalez wrote:
> > @@ -1264,8 +1264,8 @@ def validate_investigation_type(self, investigation_type):
> >          QiitaDBColumnError
> >              The investigation type is not in the ENA ontology
> >          """
> > -        investigation_types = Ontology(convert_to_id('ENA', 'ontology'))
> > -        terms = investigation_types.terms
> > +        ontology = Ontology(convert_to_id('ENA', 'ontology'))
> > +        terms = ontology.terms + ontology.user_defined_terms
> 
> Yes not really clear. BTW what's the difference between not_ontology and user_defined? 
> 
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> https://github.com/biocore/qiita/pull/522/files#r20130936