Move global variables to the class. 

Salut,

I did some changes to your code to make it more extensible. I moved some of the variables to the class
so it will be possible to have more than one keypad for aAlam (Ex at each door of the house).

   - Move global variables to the class. This will enable the possibility to have multiple keypad
   - Don't use complete path. Use relative path and add i2cKeypadMod to the library of the arduino  
     sketches
      - In the arduino IDE Sketch->Import Library -> Add Library
      - This will enable the possibility to remove duplicated files

Note. I'm just starting to use your code. I hope I will be able to send you other pull request.

A la prochaine,

Remi