Not calling python3

Hi

When I type the command according to the manual, I get:

```
Traceback (most recent call last):
  File "annotate_blast_hits.py", line 2, in <module>
    from Bio import Entrez
ImportError: No module named 'Bio'
```

I have Biopython installed. When I execute python 2.7, everything goes ok. So, I guess python3 is not calling correctly by the script.