cares_wrap: remove unused function getHostByName()

Hasn't been used in ages. Also remove its (already disabled) test.
src: centralize class wrap/unwrap

While almost all cases were handled by simple WRAP/UNWRAP macros, this
extends those to cover all known occurrences.
src: don't obj->Set(Integer::New(...), val)

Don't create an Integer when setting a numeric index on an object or an
array, use the version of v8::Object::Set() that takes an uint32_t.

Change the types of the variables from int to uint32_t and clean up
some code consistency issues while we're here.
src: fix build break from generic macro name

WRAP is too generic a macro name and causes the build to fail from
conflicts. They have been prepended with NODE_.