[chore] Bump to 0.7.0, beta. (#105)

As best as I can tell, this is feature complete (every "must" in the spec is fulfilled).

I still want to add more tests and particularly generated unit tests, but I feel confident bumping this to beta at this point.

setup.py

@@ -25,7 +25,7 @@
 
 setup(
     name='gapic-generator',
-    version='0.6.0',
+    version='0.7.0',
     license='Apache 2.0',
     author='Luke Sneeringer',
     author_email='[email protected]',
@@ -51,7 +51,7 @@
         ':python_version<"3.7"': ('dataclasses >= 0.4',),
     },
     classifiers=(
-        'Development Status :: 3 - Alpha',
+        'Development Status :: 4 - Beta',
         'Environment :: Console',
         'Intended Audience :: Developers',
         'License :: OSI Approved :: Apache Software License',