rewrite archive_xlog to make it simpler

The purpose of archive_xlog is to archive and compress a WAL segment,
not to have a big script that could handle any setup including
wal-shipping. It is better to let the user integrate it with a another
script to intregrate PITR within the target setup.
add a cleanup function on exit in backup_pitr

When the base backup exits on error, cleanup the target directories so
that it does not interfere in the list_pitr output
fix messages and comments in list_pitr
many fixes and improvements

  * general:
    - improve documentation to reflect latest changes
    - update version number in RPM spec file, use the next release
      number
    - backport debian package conf from v1 branch
  * archive_xlog:
    - always use gzip -4 to compress: remove options configuring the
      compress program
  * restore_xlog:
    - do not detect the local machine, add -L switch and make -h
      overwrite it local conf
    - make it have the same switch names as archive_xlog
  * backup_pitr:
    - add a fixed support for 9.2 as pg_tablespace has changed
  * list_pitr:
    - show more information, like tablespaces
    - fix error messages
    - fix the display of stop time when using SSH
  * pitr_mgr: reflect changes made to underlying action scripts
  * purge_pitr:
    - fix typos in messages
    - fix filtering regexs to select wal files
  * restore_pitr:
    - improve the display of usage
    - allow to pass the archive_xlog.conf path with -C
    - allow to given a custom restore_command
    - fix the empty directory check on tablespaces where exit failed
      because of a subshell
    - rework the creation of recovery.conf