Remove pbr import from fuel_agent's setup.py

Importing pbr in setup.py prevents installing
fuel_agent into clean environment (without pbr).

Change-Id: I2734b3cd97ddde7d243b71c3a7112e2519b7b7e2
Closes-Bug: #1472082

fuel_agent/hooks.py

@@ -0,0 +1,21 @@
+# Copyright 2015 Mirantis, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+
+def setup_hook(config):
+    import pbr
+    import pbr.packaging
+
+    # this monkey patch is to avoid appending git version to version
+    pbr.packaging._get_version_from_git = lambda pre_version: pre_version

setup.cfg

@@ -32,6 +32,11 @@ autodoc_index_modules = True
 # from other subprojects in this repository
 skip_git_sdist = True
 
+[global]
+setup-hooks =
+    pbr.hooks.setup_hook
+    fuel_agent.hooks.setup_hook
+
 [build_sphinx]
 all_files = 1
 build-dir = doc/build

setup.py

@@ -14,13 +14,6 @@
 
 import setuptools
 
-import pbr
-import pbr.packaging
-
-
-# this monkey patch is to avoid appending git version to version
-pbr.packaging._get_version_from_git = lambda pre_version: pre_version
-
 
 setuptools.setup(
     setup_requires=['pbr'],