O fmt=opac deve retornar "fulltexts"

[robertatakenaka]

What's this PR do?

Faz com que o "fulltexts" volte a ser retornado

Where should the reviewer start?

articlemeta/export.py

How should this be manually tested?

from articlemeta.client import ThriftClient
cl = ThriftClient()
article = cl.document(code='S0074-02761929000100003', collection='scl', fmt='opac')
article.data['fulltexts']

Retorno esperado:

{"pdf": 
{"fr": "http://www.scielo.br/pdf/mioc/v22n1/fr_tomo22(f1)_135-139.pdf",
"pt": "http://www.scielo.br/pdf/mioc/v22n1/tomo22(f1)_135-139.pdf"},
"html": 
{"pt": "http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0074-02761929000100003&tlng=pt"}}

Any background context you want to provide?

"fulltexts" foi erroneamente removido ao solucionar #116.

What are the relevant tickets?

Fixes #149

Screenshots (if appropriate)

n/a

Questions:

n/a

tk149