Doesn't work well when package name doesn't match module name

Great tool! I'm running into this problem though.
Package name is django-clickbank but module is django_clickbank.

Sureiya/django-clickbank@e671358bf03d0901a4c9c358b2b8a707c680d22f

```sh
(django_clickbank)kin@boxed-xawesome:~/Work/repositories/django-clickbank$ changes --tox django_clickbank install
What is the release version for "django_clickbank" [Default: 0.1.2]: 
warning: sdist: standard file not found: should have one of README, README.rst, README.txt

Cannot find sdist dist/django_clickbank-0.1.2.tar.gz
INFO:changes.cli:Successfully installed django_clickbank sdist
```