Installing snappi on windows requires msvc++ compiler

[Rangababu-R]

currently grpc-tools is a dependent package for snappi library and it requires Microsoft visual studio c++ compiler to be available on Windows OS.
If unavailable the installation fails.

[ajbalogh]

--prefer-binary bypasses the need for msvc++ compiler - is there a reason why this was commented out in the requirements.txt?

[Rangababu-R]

--prefer-binary bypasses the need for msvc++ compiler - is there a reason why this was commented out in the requirements.txt?

@ajbalogh While working on the black installation issue on python2.7, was trying different combinations to figure out the issue, this was commented and missed to uncomment back. will revert it back

[Rangababu-R]

Thanks for pointing it out