Removed unreferenced files.

[canoc3@lxc2dev3d2 CASTOR]$ grep -rl DbSegmentCnv .
./nbproject/configurations.xml
./nbproject/private/configurations.xml
./castor/db/cnv/DbSegmentCnv.cpp
./castor/db/cnv/DbSegmentCnv.hpp
./.git/index
./.git/objects/pack/pack-a749e3127a204825b5c252b2db64ec64d9c957e8.pack