Use git tags for version

Info.plist

@@ -22,8 +22,6 @@
 	<string>MacTimeLog</string>
 	<key>CFBundlePackageType</key>
 	<string>APPL</string>
-	<key>CFBundleShortVersionString</key>
-	<string>0.3-alpha</string>
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>DTCompiler</key>

setup.py

@@ -12,18 +12,28 @@
 from plistlib import Plist
 
 
-def generate_plist(plist_file):
-    """Read plist from file and set CFBundleVersion to HEAD commit hash"""
+def git(*args):
+    result = None
     try:
-        commit_hash = subprocess.check_output(
-                ['git', 'rev-parse', '--short', 'HEAD']).strip()
+        result = subprocess.check_output(args).strip()
     except Exception, e:
-        print >> sys.stderr, ('Unable to get git commit hash for '
-                'CFBundleVersion {0}'.format(e))
-        commit_hash = 'none'
+        print >> sys.stderr, ('Unable to run git: {0}'.format(e))
+    return result
+
+
+
+def generate_plist(plist_file):
+    """Read plist from file and set CFBundleVersion to HEAD commit hash"""
+
+    version = git('git', 'describe', '--abbrev=0', '--tags')
+    commit_hash = git('git', 'rev-parse', '--short', 'HEAD')
+
+    if version is None or commit_hash is None:
+        sys.exit(-1)
 
     plist = Plist.fromFile(plist_file)
     plist.update(dict(
+        CFBundleShortVersionString=version,
         CFBundleVersion=commit_hash,
     ))
     return plist