With git:
1) git clone https://github.com/Mickaelh51/Arduino-Oregon-Library.git Oregon
2) Put the "Oregon" folder in your Arduino "libraries" folder. 

Direct download:
1) Download https://github.com/Mickaelh51/Arduino-Oregon-Library/archive/master.zip
2) Extract master.zip
3) rename folder: mv Arduino-Oregon-Library-master Oregon
4) Put the "Oregon" folder in your Arduino "libraries" folder.