Project.pm/Validator.pm: switch to refactored valid_branch_name check

Project.pm/Validator.pm: switch to refactored valid_branch_name check

Replace the haphazard regex that has become unmaintainable (and
incomplete) with a call to the new valid_branch_name function instead.

This results in more readable and maintainable code.

Be careful with the call out from Girocco::Validator as unusual
scoping is in effect while validating and an explicit call to the
actual Girocco::ValidUtil::valid_branch_name function must be used.
Together with that, be careful to avoid import name pollution too.

To make this easy, modify Girocco::Util to automatically use the
new Girocco::ValidUtil module and export its valid_branch_name
function along with all the other valid_xxx functions.

The other valid_xxx functions in Girocco::Util are just begging to
be moved into the new Girocco::ValidUtil module.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>