Search for pip.exe instead of assuming drive letter; user better message boxes
Search for pip.exe instead of assuming drive letter; user better message boxes

mrpau/installers,ruimalheiro/installers,learningequality/ka-lite-installers,benjaoming/installers,mrpau/installers,MCGallaspy/installers,benjaoming/installers,learningequality/ka-lite-installers,mrpau/installers,learningequality/ka-lite-installers,ruimalheiro/installers,ruimalheiro/installers,learningequality/installers,learningequality/installers,learningequality/installers,MCGallaspy/installers,MCGallaspy/installers,mrpau/installers,benjaoming/installers,learningequality/ka-lite-installers,learningequality/installers,benjaoming/installers,MCGallaspy/installers,ruimalheiro/installers