Add Perl support

Hi,

these commits add Perl support to Morph. It make use (and this is dependent) on presence of the Perl docker image -- please clone the repository with Dockerfile [1] here and build the image first.

[1] https://github.com/lkundrak/morph-docker-perl

Given that Scraperwiki libraries do little more than just provide a simple database interface and classic Scraperwiki never merged Perl support, the Scraperwiki support library is not present. The Docker image includes straightforward port of Python dumptruck library [2] to Perl for this purpose. It is pulled from git, but unlike for Python library the defaults are not overridden there. I found it cleaner to just use the stock version and instruct the users to specify the correct database and table names in the example code.

[2] http://search.cpan.org/dist/Database-DumpTruck/lib/Database/DumpTruck.pm

Thank you for reviewing eventually merging this!
Lubo