FileUtils: put deprecated methods at the bottom
FileUtils: tweak style and formatting
POM.java: tweak style and formatting
FileUtils#appendContents: exclude directory itself

When listing the contents of a directory, we do not want the directory
itself to be in the returned collection. First of all, it is
inconsistent with the idea of listing the directory's "contents" (i.e.,
its children). And secondly, it makes it more involved to invoke the
method recursively.
FileUtils: add myself as an author
FileUtils: remove method-level author tags
FileUtils#deleteRecursively: tweak style & javadoc
FileUtils:listContents: flesh out javadoc
FileUtils#appendContents: flesh out javadoc
FileUtils: simplify URL-to-File conversion
FileUtilsTest: update list of authors
fixup! FileUtils#appendContents: flesh out javadoc
FileUtils: improve listContents implementation

This change adds support for two optional flags: recurse and filesOnly.
If the recurse flag is true, directory contents are computed
recursively. If the filesOnly flag is true, directories themselves are
excluded from the resulting collection.

The previous listContents and appendContents method signatures have been
retained, with recurse=true and filesOnly=true, which was the default
intended behavior.

This change also fixes a bug in the implementation: directories were
being erroneously included in the result when listing inside a JAR file.
(The unit test did not catch it because it did not test with a JAR that
included any directory entries, only files in subdirectories.)
FileUtilsTest: expand testListContents()

It should test with and without recursion, and with and without
directory inclusion.
WIP