Version 0.7.3-beta.2 : Add delay (beta) + use specific httpClient method + update dependencies

Pre-release
Add delay : Add a beta feature, to add a delay to all request, or had a function that return this delay. This could be useful, in the mock feature. By default, all mock, will have a default delay. But could be also added without mock, to simulate long request.

Use all httpClient method rather than use request method, use corresponding method (get, put, delete ...). In order, to avoid issue with request method that throw a first empty error.

Update dependencies : Update to version 13 of Angular.