Provide pickup service point name for requests

Because several aspects of mod-circulation resources need to be aware of ServicePoints, we need to make mod-circulation handle these natively.

This will include:

• Creating a ServicePoint class for mod-circulation to use internally (similar to Item, User, etc)
• Creating a ServicePointRepository class for abstracting the retrieval of ServicePoint objects
• Creating the appropriate mock resources for testing
• Other supporting infrastructure, following the current patterns employed by mod-circulation

Use case to be covered initially:

• adding the SP name to the collection of requests endpoint (for the CSV export) for pickupServicePoint

Next in the following uses will be covered within the specific issues:

• validation when creating/updating (POST/PUT) a request with pickupServicePoint (CIRC-152)

And finally:

• checkInServicePoint/checkOutServicePoint validation during creating/updating (POST/PUT) a loan (CIRC-150)
• checkInServicePoint/checkOutServicePoint validation during check-out by barcode (CIRC-154)
• adding the SP name to the collection of loans endpoint (for closed loans view) for checkInServicePointId and checkOutServicePointId (CIRC-150)