feat: support HttpClient and add tests

[wardbell]

Three phases

1. Add tests of existing code before adding Angular HttpClient support
2. Catch up on important outstanding PRs and issues against current code.
3. Add HttpClient

Phases 1 & 2 are in the first commit

• add tests
• refactor existing code to support tests
• correct bugs and clarify choices as result of test
• add new configuration options
• POST commands/resetDb passes the request to your resetDb method so you can optionally reset the database dynamically to arbitrary initial states (issue #128)
• when HTTP method interceptor returns null/undefined, continue with service's default processing (pr #120)
• reorganize files into src/app and src/in-mem folders
• adjust gulp tasks accordingly

Phase 3 is in the 2nd and 3rd commits (kept separate because of the significant refactoring in the 2nd commit).

[damsorian]

Nice! What is the approximate release date?

[wardbell]

Merging and releasing now!

[wardbell]

Critical if you upgrade to this version and you're using SystemJS you must tell it about the location of the HttpClient module's umd.js file for @angular/common/http which is at

      '@angular/common/http': 'npm:@angular/common/bundles/common-http.umd.js',

Otherwise, you'll get a 404 when it tries to load the HttpClientModule WHICH IT WILL EVEN IF YOU ARE STICKING WITH Http