fix for to_record ItemFulfillmentPackageList
added deposit other list and deposit cashback list
Fix Customer field references and + payment_method to SalesOrder

See https://system.netsuite.com/help/helpcenter/en_US/srbrowser/Browser2014_1/schema/record/customer.html
Adding update action to CustomRecord
support passing in request-level credentials
update all actions to support request-level credential config
fix stubs to handle newly desplatted args
Adding support for login action
Removing role from authentication header

Caused error with customer service center logins. Going to
do some additional tests with live NS instances and see
if this causes any issues.
Removing search_more_with_id. This is replaced by SearchResult#results_in_batches
add upsert to account
add upsert operation to service_sale_item
Proper handling of date objects in CustomFieldList
Bumping rspec to 2.99; updating syntax to reduce deprecation warnings
Documenting get_list
Fixing getList call for non-CustomRecords
Cleaning up per-request credentials implementation

Originally implemented with #71

* no need to cache credentials hash
* no need to do any input validation for auth creds. This is the users
  responsibility
* DRYing things up a bit
CustomRecord add/update/get examples