Bug 23893: Add new_from_api and set_from_api to Koha::Object

Bug 23893: Add new_from_api and set_from_api to Koha::Object

This patch introduces the following methods to the Koha::Object class:
- set_from_api
- new_from_api

This methods are going to be used when writing API controllers that map
to the attributes to the DB schema ones.

To test:
1. Apply this patchset
2. Run:
  $ kshell
 k$ prove t/db_dependent/Koha/Object.t
=> SUCCESS: Tests pass!
3. Sign off :-D

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>