fix(service): use the aliased language key if available

Fixes #530
feat(service): allow using wildcards in language aliases

Fixes #426

This allows usage of wildcards in language aliases defined by `registerAvailableLanguageKeys`. e.g.

```
$translateProvider.registerAvailableLanguageKeys(['en', 'en_GB', 'en_US'], {
	'en_*': 'en'
});
```
tests(service): add separate test for aliases

Revert back to original tests for use() function
Use separate tests for aliases to keep tests pristine