Do not use shellescape

[tmsanrinsha]

I want to use -S option with space, e.g. -S'foo bar'.
But the string is escaped and become -S\'foo bar'\'''.
Shellescape is really needed?

[gregsexton]

It's been a long time since I wrote this. I remember testing various cases on Windows and different nix shells. I can only say that I put this in for a good reason. @AlterDepp, this is up to you. I would probably look for a better solution rather than just taking it out.

[rbong]

I've added s:Gitv_DisableShellEscape as an option. Obviously, this is not a long term solution, but until I can test on other shells hopefully it will save some headaches. I may very well revert my changes and merge this when I can test. I am leaving this open intentionally.