There seems to be an issue with version 1.3, querying for topics on
postgres returns
and error:
```
panic: pq: invalid byte sequence for encoding "UTF8"
```
Upgrading pq fixes the issue
¯\_(ツ)_/¯
This commits adds support for postgres database.
Currently two fields are stored: the bloom filter and the topic.
Only the bloom filter is actually used to query, but potentially we will
use also the topic in the future, so easier to separate it now in order
to avoid a migration.
Andrea Maria Piana
Adam Babik
Pedro Pombeiro
Adam Babik