Save and sign consent forms for patients.

Form processing steps for now:
* received POST with consent form
1. save form
2. parse patient data, get or create patient in current company
3. bind form to patient
4. add payment method for patient:
* received POST with consent form signature data
5. update form: add signature, change status (unsigned => signed), enable payment method

We will void old unsigned forms after 1 hour of inactivity (change status to expired + remove card data)