SSL support

This PQ adds SSL support to all currently available adapters. After pulling this, the wiki (https://github.com/le0pard/mongodb_logger/wiki/Mongodblogger-settings) should also be updated to reflect the new option.

Usage:
```YAML
development:
  database: my_app
  capsize: <%= 10.megabytes %>
  host: localhost
  port: 27017
  replica_set: true
  ssl: true
```

Proposed wiki addition:
```MarkDown
## ssl

### Default: false

Set to `true` to use SSL when connecting to MongoDB.
```