added 'application/x-rar-compressed' to can_handle()

this fixes the case with explicitly set archive type

before:
    $ perl -MArchive::Any -E'say for Archive::Any->new("some.file", "rar")->files'
    No handler available for type 'application/x-rar-compressed' at  /home/ksurent/perl5/perlbrew/perls/perl-5.14.2/lib/site_perl/5.14.2/Archive/Any.pm line  179, <DATA> line 1000.
    Can't call method "files" on an undefined value at -e line 1, <DATA> line 1000.

after:
    $ perl -MArchive::Any -E'say for Archive::Any->new("some.file", "rar")->files'
    1.jpg
    2.jpg
    3.jpg
test case for 6774609
Merge pull request #1 from ksurent/master

Patch for RT#83392