More than one request when changing the country.

[caioregis]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[x] Bug report  
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/psykolm22/angular-google-place/blob/master/CONTRIBUTING.md#question

Current behavior

When the country changes, autocomplete is instantiated again and a new listener is generated. This is generating an accumulation of requisitions from several countries, as chosen.

Expected behavior

Only maintain the requisition of the chosen country.

Minimal reproduction of the problem with instructions

Choose a country and search for the address. A request is made. Choose another country and search for the address. Two requisitions are made.

What is the motivation / use case for changing the behavior?

Environment

Angular version:  5.2.2
Angular Google place version : 0.0.3

Browser:
- [x] Chrome (desktop) version XX
- [ ] Chrome (Android) version XX
- [ ] Chrome (iOS) version XX
- [ ] Firefox version XX
- [ ] Safari (desktop) version XX
- [ ] Safari (iOS) version XX
- [ ] IE version XX
- [ ] Edge version XX
 
For Tooling issues:
- Node version:  8.9.4  
- Platform:  win32 x64 

Others: