Cannot set path to Git.exe if it is in a non-standard folder

[PhilipDaniels]

I have installed a portable version of MSysGit in folder C:\PublicHome\OtherApps\PortableGit.

The settings page does not permit this to be picked because it requires git (and incidentally, cygwin) to be in a certain set of well-known folders (see function GetGitLocations() in CheckSettingsLogic.cs)

I have made a fix which I will be pushing to my fork. Basically, if the user browses or types or pastes into the "git path" or "sh path" boxes we allow it if that file exists. GetGitLocations therefore still works for trying to guess where git is located upon initial install, but the user is allowed to pick anywhere.