Invoking 'data get /asterisk/core/channeltypes' caused a crash because
of an assumption of a tech's capabilities to be non-NULL. The
'Surrogate' tech, however, does have a NULL capabilities member,
resulting in a crash.

ASTERISK-27108 #close

Change-Id: I2fbe7715681f43d5565d1e1599269468c26b0e0a