Change to default file permissions

Change file permissions of the tempfile/mp3-file in Tag::MP3::ID3v2 to
default
value (as determined by umask).

File permissions will otherwise (on *nix) be 0600 due to peculiarities
of the File::Temp module.
Update Parallel::Forkmanager to v1.0.2
Merge pull request #10 from carlasplund/copyfiles

Change to default file permissions, update forkmanager module
Merge remote-tracking branch 'origin/master' into develop