Resolve the circular references.

```
# Circular bean dependency between appWebMvcConfig and userRepoImpl.
spring.main.allow-circular-references: true
```

The following may also be considered for changes:
```
# Bean overriding is necessary for TokenAuthorizationFilter.
spring.main.allow-bean-definition-overriding: true
```

These properties were introduced in #174 to resolve #153.