Error for fonts with spaces in the name

Hi, first of all thanks for the plugin!

I have downloaded the Google Font “Open Sans” (via the plugin).

However, this causes two problems:
1) the space is replaced with a “-” in the filename, this causes the data in the class-bsf-custom-fonts-render.php in line 202 to get mixed up (explode with ‘-‘).
I have renamed all font files instead of open-sans… Start with open_sans. This is part 1 of the solution

2) Only “open” is written as font-family, which is why the font cannot be found in most browsers.
I have solved it this way for now:
in line 203 I use the directory name:
$font_name = $folder;
I know, not the nicest solution but now it works.

Could you solve this a little better so that I can update the plugin again in the future?
Thanks a lot!