Add support for filename ordering (as opposed to absolute file path ordering)

Currently, the orderFile behavior allows for the sorting of a transaction's files, but it does so using the absolute path (or more accurately the results of toString from File).

We are using the sql plugin, in conjunction with the maven dependency plugin, to execute all sql scripts from our dependent projects, but needed a way to order them beyond the absolute path name. For example, we might have:

/tmp/dep-A/sql/05-foo.sql
/tmp/dep-Z/sql/01-bar.sql

We want to ensure that 01-bar.sql is executed first, however due to the name of the dependent project (dep-Z vs dep-A), 05-foo.sql would be executed first.

We've added support for this based on 1.4, and attached a diff.