Add a port for clustershell

Clustershell is a program that lets you run commands, and transfer files
to/from, many servers at the same time.  It's meant for HPC environments, but
works anywhere you have multiple machines (and can list them).

The code lives in Github, so we pull from there directly, rather than going
through pip or another repository.

ClusterShell is hard-coded to look in /etc/clustershell for system-wide
configuration, so we patch that to look in ${prefix}.

net/clustershell/Portfile

@@ -0,0 +1,52 @@
+# -*- coding: utf-8; mode: tcl; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- vim:fenc=utf-8:ft=tcl:et:sw=4:ts=4:sts=4
+
+PortSystem              1.0
+PortGroup               python 1.0
+PortGroup               github 1.0
+
+github.setup            cea-hpc clustershell 1.8.2 v
+
+categories              net python
+platforms               darwin
+license                 LGPL-2+
+maintainers             kornel.us:karl openmaintainer
+
+description             Scalable cluster administration Python framework
+long_description        ClusterShell is an event-driven open source Python \
+                        library, designed to run local or distant commands in \
+                        parallel on server farms or on large Linux clusters. \
+                        It will take care of common issues encountered on HPC \
+                        clusters, such as operating on groups of nodes, \
+                        running distributed commands using optimized execution \
+                        algorithms, as well as gathering results and merging \
+                        identical outputs, or retrieving return codes. \
+                        ClusterShell takes advantage of existing remote shell \
+                        facilities already installed on your systems, like SSH.
+homepage                http://cea-hpc.github.com/clustershell
+
+checksums               rmd160 71b101bc25fbd5ba798b439372aa6b4e72e1f898 \
+                        sha256 8db2d159db941fc278c02302ce93c5a5c5bd4ad883ad75343164668623a4fc09 \
+                        size 362843
+
+# ClusterShell does not currently support Python 3.
+python.versions         27 34 35 36 37
+python.default_version  36
+
+# setuptools is used for build/install; YAML is used for configuration.
+depends_build-append    port:py${python.version}-setuptools
+depends_lib-append      port:py${python.version}-yaml
+
+# The code (in lib/ClusterShell/Defaults.py) has a hard-coded config file 
+# search path.  We need to change this before the compile phase.
+patchfiles              patch-lib-ClusterShell-Defaults.py
+post-patch {
+    reinplace "s|@MACPORTS_PREFIX@|${prefix}|g" ${worksrcpath}/lib/ClusterShell/Defaults.py
+}
+
+# The setup script creates some example config files, but does not respect 
+# $prefix when creating those files.  I think that's because, when setup.py is
+# run, it's given $destroot as the --root.  We deal with this by moving the 
+# files ourselves, after setup.py runs.
+post-destroot {
+    move [glob ${destroot}/etc/*] ${destroot}${prefix}/etc
+}

net/clustershell/files/patch-lib-ClusterShell-Defaults.py

@@ -0,0 +1,11 @@
+--- lib/ClusterShell/Defaults.py	2016-11-21 12:50:40.000000000 -0800
++++ lib/ClusterShell/Defaults.py	2016-11-21 12:51:42.000000000 -0800
+@@ -77,7 +77,7 @@
+
+ def config_paths(config_name):
+     """Return default path list for a ClusterShell config file name."""
+-    return ['/etc/clustershell/%s' % config_name, # system-wide config file
++    return ['@MACPORTS_PREFIX@/etc/clustershell/%s' % config_name, # system-wide config file
+             # default pip --user config file
+             os.path.expanduser('~/.local/etc/clustershell/%s' % config_name),
+             # per-user config (top override)