Add Catmandu::Fix::bind::pica_patch

[nichtich]

This should result in a PICA Patch record that modifies 003A$0 and adds 004F$af:

do pica_patch
  pica_set('dc.identifier', '003A$0')
   pica_add('dc.subjects', '004F$af')
end

[nichtich]

Done as pica_diff