JAVA-279: Remove unused method

### Problem
`BasicBSONObject.put()` and `BasicDBObject.append()` are not necessary.

### Solution
Remove them

#### Why
BasicBSONObject.put() -> just calls the parent, so no need to override that method
BasicDBObject.append() -> Has the same code as the parent has, so no need to repeat that.

review @jyemin
[fix https://jira.mongodb.org/browse/JAVA-297]