Wolnelektury plugin

The plugin seems to work fine, but there is a minor issue with downloading. EPUBs, MOBIs and FB2s get correct filenames, metadata and even covers, while PDFs and TXTs get titles broken (additional 6 chars in front of the name that look like taken from base64 set, highlighted in red in the screenshot) and when I try to open them, the meassge box 'No such file or directory' pops up. And indeed there is no trace of them on my harddisk.

![broken names](https://f.cloud.github.com/assets/33378/1293785/ced09972-306c-11e3-885e-8f49b2e2b799.png)