Add EntityNote resource, contact task/note helpers and new contact/task filters

[keith-chartmogul]

Aligns the SDK with recent changes to the public v1 API for Contacts, Tasks and Notes. All changes are additive; no existing method changes its behavior or endpoint.

Notes and call logs

• New ChartMogul.EntityNote resource for /v1/notes, which supersedes /v1/customer_notes. Notes can be attached to a customer via customer_uuid or to a customer or contact via associated_object_identifier. Supports all, create, retrieve, patch and destroy, with customer_uuid, contact_uuid, type and author_email list filters.
• ChartMogul.CustomerNote is deprecated. Its five methods still call /v1/customer_notes unchanged but now emit a [DEPRECATED] warning pointing at the EntityNote equivalent.
• Customer.entityNotes and Customer.createEntityNote added; Customer.notes and Customer.createNote are deprecated with a warning.

Contacts

• New helpers Contact.tasks, Contact.createTask, Contact.entityNotes and Contact.createEntityNote. The list helpers filter by contact_uuid. The create helpers attach the task or note to the contact via associated_object_identifier unless the caller supplies customer_uuid or their own identifier.
• Contact.all documents the new email, customer_external_id and external_id filters. Contact.create no longer requires customer_uuid and data_source_uuid, and last_active_at / last_seen are covered by tests.

Tasks

• Task.create accepts associated_object_identifier, with customer_uuid now optional.
• Task.all documents the contact_uuid, assignee, due_date_on_or_after, due_date_on_or_before and completed filters. Tests confirm completed: false is serialized rather than dropped.

HTTP layer

• Resource.request now resolves with {} on a 304 Not Modified response. The API returns this with an empty body when a PATCH to /v1/notes or /v1/tasks carries nothing to update; previously superagent surfaced it as an error.

Tests and docs

• New test/chartmogul/entity-note.js suite; extended task, contact, customer, customer-note and resource suites, including assertions that the deprecation warnings fire and the legacy endpoints are still hit.
• Task fixtures now use the API's task_uuid response key, and the contact create fixture uses customer_external_id with a 201.
• README updated with a Notes and Call Logs section, a deprecated Customer Notes section, and the new contact and task filters and helpers.

No version bump in this PR; release via bin/release.sh minor after merge.

[loomchild]

[minor] Isn't this too smart - I'd repat the same thing like below for consistency.

[keith-chartmogul]

Good call, I've replaced the loop with five explicit wrappers matching the Customer.notes / Subscription.all style 👍