dep folder is up one dir

Build kept failing until I make this change. 
$ make
Scanning dependencies of target vmapextractor
[ 12%] Building CXX object CMakeFiles/vmapextractor.dir/adtfile.cpp.o
In file included from /home/mangos/server/contrib/vmap_extractor/vmapextract/adtfile.h:22:0,
                 from /home/mangos/server/contrib/vmap_extractor/vmapextract/adtfile.cpp:22:
/home/mangos/server/contrib/vmap_extractor/vmapextract/mpqfile.h:14:22: fatal error: StormLib.h: No such file or directory
compilation terminated.
make[2]: *** [CMakeFiles/vmapextractor.dir/adtfile.cpp.o] Error 1
make[1]: *** [CMakeFiles/vmapextractor.dir/all] Error 2
make: *** [all] Error 2
Merge pull request #23 from CaptSpify/patch-1

dep folder is up one dir