Fix _version.py and various version-related issues (Project-MONAI#539)

- Removed unnecessary logic in setup.py
- Fix versioneer issues

Signed-off-by: M Q <mingmelvinq@nvidia.com>
Signed-off-by: Simone Bendazzoli <simben@kth.se>

Author: MMelQin

monai/deploy/__init__.py

@@ -23,3 +23,6 @@
 from . import _version, conditions, core, exceptions, logger, resources, utils
 
 __version__ = _version.get_versions()["version"]
+
+from . import _version
+__version__ = _version.get_versions()['version']