Always include all src files if any is newer than dest file

For a single src/dest pair, always use all src files if any one is newer than the dest file.
Test util functions
Deprecate the `any-newer` task

Use the `newer` task instead.  This task now behaves the same way as the old `any-newer` task for many:1 src:dest file mappings.
Merge pull request #17 from tschaub/single-task

Deprecate the any-newer task.