Change setup.py to extract version without importing.

setup.py

@@ -17,11 +17,27 @@ limitations under the License.
 """
 
 from setuptools import setup, find_packages
+import codecs
+import os
+import re
 
-from teeth_agent import agent
+here = os.path.abspath(os.path.dirname(__file__))
+
+
+def read(*parts):
+    return codecs.open(os.path.join(here, *parts), 'r').read()
+
+
+def find_version(*file_paths):
+    version_file = read(*file_paths)
+    version_match = re.search(r"^__version__ = ['\"]([^'\"]*)['\"]",
+                              version_file, re.M)
+    if version_match:
+        return version_match.group(1)
+    raise RuntimeError("Unable to find version string.")
 
 setup(
     name='teeth-agent',
-    version=agent.AGENT_VERSION,
+    version=find_version('teeth_agent', '__init__.py'),
     packages=find_packages(),
 )

teeth_agent/__init__.py

@@ -0,0 +1,4 @@
+
+__all__ = ["__version__"]
+
+__version__ = "0.1-dev"