Project Settings do not open properly in windows from the menu, launching an empty file instead of the correct one. Switch to open_file method simplest way to resolve. Tested mac + win
Bug Fix: Linux - Cannot open project #219

This is a fix for the bug #219. The popen command was not passed the parameters in the correct order so the command would fail to execute. This would have been noticed immediately if the application had been tested on Linux. Also, popen takes a list of arguments as the first parameter which is handled better than passing in one single string.
Merge pull request #432 from jamesmelville/windows_project_settings

MavensMate -> Settings -> Project broken under windows
Merge pull request #443 from brettbatie/master

Bug Fix: Linux - Cannot open project #219