LBFactory: support custom ports in sectionLoads

@Wikia/platform-team / @drozdo 

This will simplify the DB config as the hostname-to-IP conversion will happen based on hostname only (without a port).

Examples:

```
  'host' =>
  string(17) "10.14.30.142:3306"
  'hostName' =>
  string(22) "dev-db-central-p1:3306"

  'host' =>
  string(12) "10.14.30.142"
  'hostName' =>
  string(17) "dev-db-central-p1"
```

Required by https://github.com/Wikia/config/pull/654