Issue #262: bean-doctor says version is insufficient even though it's not (versions compared as strings) (blais/beancount)

[Martin Michlmayr]

New issue 262: bean-doctor says version is insufficient even though it's not (versions compared as strings)
https://bitbucket.org/blais/beancount/issues/262/bean-doctor-says-version-is-insufficient

Martin Michlmayr:

beancount expects ply version 3.3. bean-doctor says my version is not sufficient:

```
ply : 3.11 (INSUFFICIENT)
```

This is because the versions are compared as strings.

I will open a PR with a fix