Depend on libstrictures-perl

Required for auto tests:

| 15:21:38    dh_auto_test
| 15:21:38 Can't locate strictures.pm in @INC (@INC contains: /tmp/buildd/ngcp-schema-1.002+0~20130617131622.3+wheezy~1.gbpb972b3/blib/lib /tmp/buildd/ngcp-schema-1.002+0~20130617131622.3+wheezy~1.gbpb972b3/blib/arch /etc/perl /usr/local/lib/perl/5.14.2 /usr/local/share/perl/5.14.2 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.14 /usr/share/perl/5.14 /usr/local/lib/site_perl .) at /usr/share/perl5/Module/Runtime.pm line 317.
| 15:21:38 BEGIN failed--compilation aborted at t/compile.t line 1.