npm install fail on Jessie

[paulgeringer]

This is very similar to #5 (though my french is a bit rusty). I was hitting the following error when running npm install:

> ioctl@1.0.1 install /home/retropie/node-virtual-gamepads/node_modules/ioctl
> node-gyp rebuild

make: Entering directory '/home/retropie/node-virtual-gamepads/node_modules/ioctl/build'
  CXX(target) Release/obj.target/ioctl/src/ioctl.o
In file included from ../src/ioctl.cpp:3:0:
../node_modules/nan/nan.h:324:47: error: ‘REPLACE_INVALID_UTF8’ is not a member of ‘v8::String’
   static const unsigned kReplaceInvalidUtf8 = v8::String::REPLACE_INVALID_UTF8;
                                               ^
ioctl.target.mk:82: recipe for target 'Release/obj.target/ioctl/src/ioctl.o' failed
make: *** [Release/obj.target/ioctl/src/ioctl.o] Error 1
make: Leaving directory '/home/retropie/node-virtual-gamepads/node_modules/ioctl/build'

The solution was to upgrade node-gyp to the latest version (found nodejs/nan#414), after which npm install worked without errors.

Not sure if there is anything to change with this project's setup, but I'm adding this issue just so anyone else who runs into this issue has a solution.

[robsdedude]

Would you be so kind to create a PR, adding this hint to TROUBLESHOOTING.md?

[robsdedude]

Closing this. I added a hint in TROUBLESHOOTING.md to check the issues.