Fix blurb import in the runpy interface (#22)

Author: hugovk

src/blurb/__main__.py

@@ -1,5 +1,5 @@
-"""Run blurb using `python3 blurb/`."""
-import blurb
+"""Run blurb using ``python3 -m blurb``."""
+from blurb import blurb
 
 
 if __name__ == '__main__':

tox.ini

@@ -19,3 +19,5 @@ commands =
       {posargs}
     blurb test
     blurb help
+    {envpython} -I -m blurb test
+    {envpython} -I -m blurb help