Uses PBKDF2-SHA256 instead of plain SHA256

Fixes #192

setup.py

@@ -89,6 +89,8 @@ setup(
         "tzlocal>=1.1",
         "PyYAML>=3.11",
         "keyring>=3.3",
+        "passlib>=1.6.2",
+        "python-dateutil>=2.2"
     ] + [p for p, cond in conditional_dependencies.items() if cond],
     long_description=__doc__,
     entry_points={