Add versioning to imgtool

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/scripts/imgtool/__init__.py b/scripts/imgtool/__init__.py
index 107921f..8f6e848 100644
--- a/scripts/imgtool/__init__.py
+++ b/scripts/imgtool/__init__.py
@@ -11,3 +11,5 @@
 # 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.
+
+imgtool_version = "1.4.0a3"
diff --git a/scripts/imgtool/main.py b/scripts/imgtool/main.py
index 22bce62..27697ae 100755
--- a/scripts/imgtool/main.py
+++ b/scripts/imgtool/main.py
@@ -20,7 +20,7 @@
 import getpass
 import imgtool.keys as keys
 import sys
-from imgtool import image
+from imgtool import image, imgtool_version
 from imgtool.version import decode_version
 
 
@@ -249,6 +249,11 @@
         return None
 
 
+@click.command(help='Print imgtool version information')
+def version():
+    print(imgtool_version)
+
+
 @click.command(cls=AliasesGroup,
                context_settings=dict(help_option_names=['-h', '--help']))
 def imgtool():
@@ -259,6 +264,7 @@
 imgtool.add_command(getpub)
 imgtool.add_command(verify)
 imgtool.add_command(sign)
+imgtool.add_command(version)
 
 
 if __name__ == '__main__':
diff --git a/scripts/setup.py b/scripts/setup.py
index 0eeeba5..a58e6b0 100644
--- a/scripts/setup.py
+++ b/scripts/setup.py
@@ -1,8 +1,9 @@
 import setuptools
+from imgtool import imgtool_version
 
 setuptools.setup(
     name="imgtool",
-    version="1.3.1",
+    version=imgtool_version,
     author="The MCUboot commiters",
     description=("MCUboot's image signing and key management"),
     license="Apache Software License",