kohaRest: Feature parity with Koha db driver.

* module/VuFind/src/VuFind/ILS/Driver/KohaRest.php: new file: driver
  using a Koha REST API rather than direct db connections.
KohaRest: tidy dependencies, init.

* module/VuFind/src/VuFind/ILS/Driver/KohaRest.php: drop PDO,
  PDOException requirements.
  ($ws_host): rename to $host.
  ($ws_app): rename to $api_path.
  ($db): remove.
  ($locCodes): rename to $locations.
  ($default_location): new variable.
  ($dateConverter): new variable.
  (init): make more robust, use new names, add debugging.
  (makeRequest): use new names.
KohaRest: implement further number of methods.

* module/VuFind/src/VuFind/ILS/Driver/KohaRest.php (toKohaDate) (getConfig)
  (getPickupLocations) (getDefaultPickupLocation) (placeHold)
  (getCancelHoldDetails) (cancelHolds): new methods.
KohaRest: add default Config for driver.

* config/vufind/KohaRest.ini: add new file.
KohaRest: implement API based renewals.

* module/VuFind/src/VuFind/ILS/Driver/KohaRest.php (getMyTransactions):
  return 'item_id' and 'renewable'.
  (getRenewDetails) (renewMyItems): new procedures.
KohaRest: tidy copyright, remove debug tools, etc.

* module/VuFind/src/VuFind/ILS/Driver/KohaRest.php