Fix paths with spaces on vs2015 gdb frontend

[vosen]

No description provided.

[vadimcn]

I found that there's a similar problem with WorkingDirectory. A bit surprised you didn't hit that... did you put something without spaces in the "Working directory" box?

[vosen]

I don't have the access to system with vs2015 + Visual Rust at the moment, but I remember making sure that project-specific Debug settings are empty/default and the project is on the path with spaces.
With exe path being correct and working dir unset, working dir is left up to ms plugin/gdb and it should correctly default to the location of .exe.
I didn't check explicitly setting working dir and this one might be buggy. I'll check it later today, when I have the access the right environment.