Can't currently install font bundle 
_Summary:_ I am not sure whether the problem is caused by an obsolete plugin with Sketch 39.1 or by the way it acts under OS 10.11.6 on my rather old iMac. Important: Icon Font plugin was fully operational under earlier versions of Sketch and/or OSX and stopped working after recent updates of and/or OS.

_Steps to Reproduce:_ Activating Sketch top menu: Plugins / Icon Font / Install a Font-bundle / Browsing to font files' folder.

_Expected Results_ TTF font' files available to Sketch/IconFont file browser.

_Actual Results:_ TTF font files show grayed out and are not accessible to Sketch/IconFont file browser. Important: Those TTF files are fully accessible from Finder.

System Info:

Bundle Identifier: com.bohemiancoding.sketch3

Build Version: 39.1

Build Number: 31720

OS Version: 10.11.6
