make it possible to dump data from postgresql to a intelmqdump file format

[aaronkaplan]

Reasoning: if there is data in the postgresql DB which can not be further processed, I'd like to have a feature where I can SELECT (sql select) these rows and export them into an intelmqdump tool format JSON file. This file can then be taken by intelmqdump and put into any queue in the intelmq pipeline.

In summary - this allows for the re-injection of data from postgresql into the while intelmq system.