src/lib/dhcp/libdhcp++.cc
    Cleaned up necessary exception decls

src/lib/dhcp/option.h
    Added commentary for SkipThisOptionError

src/lib/dhcp/option_definition.cc
    Cleaned up unnecessary exception decls

src/lib/dhcp/option_string.cc
    Replaced NULL with nul

src/lib/testutils/gtest_utils.h
    Added emissions of exception type name