Support for koji profiles.

This patch is dmach's patch [1] refactored according to mikem's comments [2].

[1] https://lists.fedoraproject.org/pipermail/buildsys/2015-August/004857.html
[2] https://lists.fedoraproject.org/pipermail/buildsys/2015-October/004900.html

Signed-off-by: Tomas Mlcoch <tmlcoch@redhat.com>

docs/profiles.rst

@@ -0,0 +1,74 @@
+=============
+Koji Profiles
+=============
+This document describes how to work with koji profiles.
+
+
+Command Line Interface
+======================
+Koji client allows connecting to multiple koji instances from CLI
+by using profiles. The default profile is given by executable file name,
+which is 'koji'.
+
+To change koji profile, you can:
+
+ * run koji with --profile=$profile_name argument
+ * change executable file name by symlinking $profile_name -> koji
+
+
+Configuration Files
+===================
+Configuration files are located in following locations:
+
+ * /etc/koji.conf
+ * /etc/koji.conf.d/\*.conf
+ * ~/.koji/config.d/\*.conf
+ * user-specified config
+
+Koji reads them, looking for [$profile_name] sections.
+
+
+Using Koji Profiles in Python
+=============================
+Instead of using koji module directly,
+get profile specific module by calling::
+
+    >>> mod = koji.get_profile_module($profile_name)
+
+This module is clone of koji module with additional
+profile specific tweaks.
+
+Profile configuration is available via::
+
+    >>> mod.config
+
+
+Example
+-------
+
+Print configuration::
+
+    import koji
+
+    fedora_koji = koji.get_profile_module("koji")
+    ppc_koji = koji.get_profile_module("ppc-koji")
+
+    for i in (fedora_koji, ppc_koji):
+        print "PROFILE: %s" % i.config.profile
+        for key, value in sorted(i.config.__dict__.items()):
+            print "    %s = %s" % (key, value)
+        print
+
+
+Use ClientSession::
+
+    import koji
+
+    koji_module = koji.get_profile_module("koji")
+    client = koji_module.ClientSession(koji_module.config.server)
+    print client.listTags()
+
+
+TODO
+====
+* consider using pyxdg for user config locations