Create Process endpoint

[bdromard]

This pull request provides an API endpoint to query information about a process evaluated by Scaphandre. The process can be queried through its process ID.

The API response will give information about the embedded impacts (GWP, ADP, PE) of the process, measured against the hardware specifications of the device where the process is executed.

It allows to query a process' information through a Process class, which validates the queried process ID, and calculates the different embedded impacts.

Associated tests are available in /tests/api/test_api_unit.py.

Associated to issue #48.

Remains to implement :

• [ ] Evaluation of usage impacts
• [ ] Evaluation of embedded impacts for a process for storage