Added the `addProject` method.

Includes:
- The `addProject` method
- The test method `testAddProject`
- A fixture in test_connection to create a valid project object.
Added the method `delProject`.

Includes the test method `testDelProject`
Added the method `getProjectId`.
Added the method `getProject`.

It's not really a SOAP call but a search in the user projects.
Now it's used to simplify some tests.
Added the method `updateProject`.

Includes the test method `testUpdateProject`