fix: #4 add release candidate version

setup.py

@@ -2,7 +2,7 @@
 import os
 
 from setuptools import find_packages, setup
-
+from subprocess import check_output
 
 with open(os.path.join(os.path.dirname(__file__), 'requirements.txt')) as f:
     requirements = ''
@@ -11,9 +11,16 @@ with open(os.path.join(os.path.dirname(__file__), 'requirements.txt')) as f:
             requirements += line
 
 
+def version_format():
+    branch = check_output('git branch --show-current'.split()).decode('utf-8').strip()
+    if branch == 'master':
+        return '{tag}.dev{commitcount}'
+    return '{tag}'
+
+
 setup(
     name='prozorro-metrics',
-    version_format='{tag}',
+    version_format=version_format(),
     setup_requires=['setuptools-git-version'],
     packages=find_packages('src'),
     package_dir={'': 'src'},