Document (test) dependency on File::Slurp
tests: Do keys() on assigned hash

The use of keys(fun()) isn't supported by Perl before 5.14, it
seems. This (hopefully) solves cpan smoker issues on Perl
versions earlier than that.
Update synopsis in WWW::SVT::Play::Video

The synopsis wasn't updated after support for HLS/HDS was added.
Use our instead of "use vars" in bin/svtplay
Prepare release 0.11