Fix `FileStationListEndpoint().List()` when used with `pattern`

[FroggieFrog]

My DSM 6 and my DSM 7 machines always returned a 502 BadGateway when I tried to check if a file is present.

The issue is a not correct formatted parameter pattern. The doc says:

2. You can use "," to separate multiple glob patterns.

But the lib always encoded the pattern as ["file","secondFile"] or ["file"] instead of the correct file,secondFile or file.

• also fixed/adjusted some doc-comments
• filesize is now returned

[plneto]

Thanks for fixing this.