Files with encodings other than utf-8 unicode are not imported at all

[jeanslack]

What operating system are you using?
Linux

What version of Videomass are you using and how did you install or run it?
Running from source code.

Describe the bug
Loading some video files raised traceback UnicodeDecodeError: 'utf-8' codec can't decode byte 0xd0 in position 804: invalid continuation byte. This error was not handled by the program and passed silently into the terminal.

We noticed that metadata on media files written with non-UTF-8 encoding characters causes this problem.

At least, To ensure that the problem does not pass silently need to handle the UnicodeDecodeError exception. Fixed by #295

Add a function that allows you to change character encoding on the fly to be able to work even on files with non-standard encodings. Fixed by #297