Support for Warsaw WSE quotes via stooq.pl API

Adds support for Warsaw Stock Exchange quotes via public API provided
by http://stooq.pl website (Polish language only).

The patch was originally posted almost two years ago on CPAN [1] by
Michał Fita but for some reason got completely ignored. However it has
been included in SUSE/OpenSUSE [2]. Similarly, I myself have also
requested this very package to be included in similar fashion in
Ubuntu, to no avail [3].

[1] https://rt.cpan.org/Public/Bug/Display.html?id=64474
[2]
https://build.opensuse.org/package/revisions?package=perl-Finance-Quote&
project=devel%3Alanguages%3Aperl
[3]
https://bugs.launchpad.net/ubuntu/+source/libfinance-quote-perl/+bug/105
2597