Issue title: Path Suggestions include  Excluded Folders and Files 
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From https://github.com/Microsoft/vscode/issues/20557

**TypeScript Version:**  2.2.1

```json
{
    "exclude": [
        "node_modules"
    ]
}
```

```ts
import * as  x from './|'
```

Request `completions` from TSServer at the `|`

**Expected behavior:**
No folder suggestion for `node_modules` is returned since the folder has been explicitly excluded

**Actual behavior:**
An entry for `node_modules` is included in the results
 Comments: 
 Comment 0: This is the intended behavior; `exclude` is just a filter on `include` and doesn't prevent those files from entering the compilation via `import`
{'source': 'GithubIssues', 'repo_name_with_owner': 'microsoft/TypeScript', 'issue_id': 209951944, 'repo_stars': 85566.0}