Unhandled exception: UnicodeEncodeError: 'latin-1' codec can't encode characters

### Step 1: Please describe your environment

* ZeroNet version: r4473
* Operating system: Raspbian
* Web browser: FF

### Step 2: Describe the problem:

debug.log shows multiple errors during startup

> INFO ConnServer Server port opened ipv4: False, ipv6: False
> ERROR - Unhandled exception: UnicodeEncodeError: 'latin-1' codec can't encode characters in position 99-109: ordinal not in range(256) in greenlet.py line 766 > Bigfile/BigfilePlugin.py line 830 > Site.py line 785 > FilePack/FilePackPlugin.py line 106 > SiteStorage.py line 390 > genericpath.py line 30

it was added not many seconds before i loaded /plugins page which does not list any plugins, then after maybe one minute, the plugin list appeared.

Start by reproducing startup and opening the /plugins page while reviewing debug.log. Trace the reported exception through greenlet.py, Bigfile/BigfilePlugin.py, Site.py, FilePack/FilePackPlugin.py, and SiteStorage.py; done means startup completes without the UnicodeEncodeError and the plugin list loads reliably.

Scritto dal modello di indicizzazione a partire dal testo della issue.