Bug 24211: Compress/uncompress translation files

Bug 24211: Compress/uncompress translation files

This patch adds the ability to compress/uncompress
translations files.

On update/install the files are uncompressed first

The only gain is to use less space.

To test:
1) Apply the patch
2) Go to misc/translator
3) Try it
   $ ./translate compress fr-FR (check po/*.gz)
   $ ./translate uncompress fr-FR ( check normal files)
4) Try again with verbose mode
   $ ./translate compress fr-FR -v (list compressed files)
   $ ./translate uncompress fr-FR -v (list uncompressed files)
5) Try update compressed files
   $ ./translate compress fr-FR
   $ ./translate update fr-FR (result is uncompressed)
6) Try install compressed files
   $ ./translate compress fr-FR
   $ ./translate install fr-FR
7) Try compress all
   $ ./translate compress  (add '-v' for verbose output)
8) Try uncompress all
   $ ./translate uncompress  (add '-v' for verbose output)

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Bouzid Fergani <bouzid.fergani@inlibro.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>