Specify Perl version prerequisite in Build.PL
Do not `shift` from an array reference

This is an experimental feature introduced in 5.14 and
the module is supposed to work in 5.12.
Add configure-phase dependency on Software::License

At least in 5.18, without it M::B didn't recognize GPL_3
in Build.PL's license field.
Increase version to 0.02
Add Travis-CI config