Issue title: IE8 Compatibility
 Issue body: Doesn't appear that angucomplete-alt is compatible with wdavis@example.com.  I know, IE8 sucks, but many of us still have to support the darn thing.

 Comments: 
 Comment 0: There is a way to run it.
1. You have to use angular 1.2.28. Angular does not support IE8 anymore. So you have to downgrade it.
2. Only part that fails in angucomplete-alt is the part that uses promises.
Change this code into the following:
```js
scope.remoteApiHandler(str, httpCanceller.promise)
  .then(httpSuccessCallbackGen(str))
  .catch(httpErrorCallback);
```

```js
/* IE8 compatible */
scope.remoteApiHandler(str, httpCanceller.promise)
  ['then'](httpSuccessCallbackGen(str))
  ['catch'](httpErrorCallback);
```
 Comment 1: Sweet.  We are on 1.2.28.  I'll try changing that bit of code.  Thanks!!!
 Comment 2: See also #191 
{'source': 'GithubIssues', 'repo_name_with_owner': 'ghiden/angucomplete-alt', 'issue_id': 94139454, 'repo_stars': 950.0}