Allow to use different API source (Lomadee)

The base URL was:

```
[env].buscape.com/service/[method]/[app_id]/?[parameter]=[value]
```

Now it is:

```
[env].buscape.com/service/[method]/[api]/[app_id]/?[parameter]=[value]
```

The api parameter is optional.
Small refactoring
fixing the gems source (use of https)
trully using the api in json format (for default)
merge with remote
little refactoring
fixing the merge
Merge pull request #3 from douglascamata/master

Adding support to use the JSON api and different API source (Lomadee or Buscape), fix on Gemfile and some good refactoring