NbOAuth2AuthStrategy and Hash Location Strategy

### Issue type

**I'm submitting a ...** (check one with "x")

* [x ] bug report
* [ ] feature request

### Issue description

**Current behavior:**
I have to use hash location strategy in my Angular 8 app. The app uses NbOAuth2AuthStrategy to login via Azure AD. The configured redirect uri is `/#/auth/callback`. But instead of adding the access token to this uri (`/#/auth/callback#access_token=ey....`) it cuts the auth/callback and navigates to `/#access_token=ey...` which does not work.

**Expected behavior:**
see above

**Steps to reproduce:**
- configure hash location strategy
- configure NbOAuth2AuthStrategy for azure ad

### Other information:

**npm, node, OS, Browser**
node v12.13.0
npm 6.12.0
OS: Windows 10
Browser: Same behavior in Chrome, Edge, Firefox

**Angular, Nebular**
```
"dependencies": {
"@agm/core": "^1.1.0",
"@angular/animations": "^8.0.0",
"@angular/cdk": "^8.0.0",
"@angular/common": "^8.0.0",
"@angular/compiler": "^8.2.14",
"@angular/core": "^8.2.14",
"@angular/forms": "^8.2.14",
"@angular/platform-browser": "^8.2.14",
"@angular/platform-browser-dynamic": "^8.2.14",
"@angular/router": "^8.2.14",
"@nebular/auth": "4.1.2",
"@nebular/eva-icons": "4.1.2",
"@nebular/security": "4.1.2",
"@nebular/theme": "4.1.2",
"@swimlane/ngx-charts": "^12.1.0",
"bootstrap": "4.3.1",
"classlist.js": "1.1.20150312",
"core-js": "2.5.1",
"eva-icons": "^1.1.0",
"intl": "1.2.5",
"ionicons": "2.0.1",
"nebular-icons": "1.1.0",
"ng-circle-progress": "^1.4.1",
"ng2-completer": "^3.0.3",
"ng2-smart-table": "^1.5.0",
"ngx-image-cropper": "^3.0.1",
"node-sass": "^4.12.0",
"normalize.css": "6.0.0",
"pace-js": "1.0.2",
"roboto-fontface": "0.8.0",
"rxjs": "6.5.2",
"rxjs-compat": "6.3.0",
"socicon": "3.0.5",
"typeface-exo": "0.0.22",
"web-animations-js": "github:angular/web-animations-js#release_pr208",
"zone.js": "~0.9.1"
}
```