Initial spec/class for SendGridApi

Class is loading and Specs are now properly generating... and passing!
- Edits composer.json: updates psr-4 to `"ErikAybar\\SendGridWeb\\": "src/ErikAybar/SendGridWeb"`
    - phpspec was not seeing already created classes using the previous `"src"` path
    - Updates project name
- Adds phpspec.yml
- Specs
    - it_is_initializable
    - it_should_have_a_base_url