FlatArchivePath extension can set task PATH env.

Hadupils::Extensions::FlatArchivePath derives from
its namespace cohabitant 'Flat', but scans all its
archive assets for a "bin" directory.  Any such archives
are identified, and they will be added to the PATH environment
variable experienced by hadoop child tasks (via the
mapred.child.env config variable).

Hadupils::Util provides some (not directly tested) utilities
for reading gzipped tar archives.  This is indirectly tested
via the tests for the above class.
Hive command uses FlatArchivePath extension

We want "hadupils hive" to use the FlatArchivePath for
hadoop-ext instead of Flat, so that archives with "bin"
top-level directories can have them automatically on the
task PATH environment variable at job runtime.  This,
I command!
Bump to version 0.3

And updated the changelog