Decrease package version to 0.1.0

Seems like a better idea to start the version cycle for this package with v0.1.0, especially as version 1.0.0-rc1 was never tagged or published.

Author: sgerrand

setup.py

@@ -5,7 +5,7 @@
 
 setup(
     name="duffel-api",
-    version="1.0.0-rc1",
+    version="0.1.0",
     author="Duffel Engineering",
     author_email="[email protected]",
     description="Client library for the Duffel API",