[CB-3798] Fixed issue where childprocess.spawn failed for paths with quotes

The problem only exists with spawn calls...
Spawn seems to be able to handle paths with spaces without the use of quotes. Quotes actually break spawn.
While exec requires quotes for paths with spaces.
Bit of weird behaviour here, but it seems to be in order now...

@tracyli Can we please test signing/debug token scenarios for paths with and without spaces to be absolutely safe :).