Update sysutils/fabric to 1.6.0.

pkgsrc changes:
---------------
- Update dependency to py-paramiko to 1.10.0

upstream changes:
-----------------

2013-03-01: released Fabric 1.6.0

2013-03-01: released Fabric 1.5.4

[Bug] #844: Account for SSH config overhaul in Paramiko 1.10 by e.g.
updating treatment of IdentityFile to handle multiple values.
This and related SSH config parsing changes are backwards
incompatible; we are including them in this release because they do fix
incorrect, off-spec behavior.

[Bug] #843: Ensure string pool_size values get run through int() before
deriving final result (stdlib min() has odd behavior here...).
Thanks to Chris Kastorff for the catch.

[Bug] #839: Fix bug in rsync_project where IPv6 address were not always
correctly detected. Thanks to Antonio Barrero for catch & patch.

[Bug] #587: Warn instead of aborting when env.use_ssh_config is True but
the configured SSH conf file doesn't exist. This allows multi-user
fabfiles to enable SSH config without causing hard stops for users lacking
SSH configs. Thanks to Rodrigo Pimentel for the report.

[Feature] #821: Add remote_tunnel to allow reverse SSH tunneling
 (exposing locally-visible network ports to the remote end).
Thanks to Giovanni Bajo for the patch.

[Feature] #823: Add env.remote_interrupt which controls whether Ctrl-C is
forwarded to the remote end or is captured locally
(previously, only the latter behavior was implemented).
Thanks to Geert Jansen for the patch.


(gls)