The kernel crash is a bug which arises from deep recursion in string pattern matching. It has been fixed in version 10.1.0 and later, by updating to a more modern version of the PCRE library and switching to a non-recursive approach in certain cases.
I am not aware of a workaround applicable to older versions, but it doesn't crash with 10.1 and 10.2:
Import["http://nanocrystallography.research.pdx.edu/static/mcodcif/1/50/41/1504113.cif"]
// Short
(* {"_656" -> ".", "_656" -> ".", <<154>>, "_symmetry_space_group_name_H-M" -> "P -1"} *)