Generate version info from git tags

Use the "setuptools_scm" package to automatically generate the version of the
package as well as the corresponding variable available in the code. This fixes
issue #86 while still leaving open the Sphinx part.

Author: ehrenfeu

bioformats/__init__.py

@@ -12,7 +12,7 @@
 from __future__ import absolute_import, unicode_literals
 
 try:
-    from _version import __version__
+    from ._version import version as __version__
 except ImportError:
     # We're running in a tree that doesn't have a _version.py, so we don't know what our version is.
     __version__ = "0.0.0"

setup.py

@@ -39,5 +39,8 @@
         "bioformats"
     ],
     url="http://github.com/CellProfiler/python-bioformats/",
-    version="1.4.0"
+    setup_requires = ['setuptools_scm'],
+    use_scm_version = {
+        "write_to": "bioformats/_version.py",
+    },
 )