Merge pull request cloudant#443 from cloudant/prepare-for-2.12.0-release

Prepare version 2.12.0 release.

- [NEW] Added option for client to authenticate with IAM token server.

- [FIXED] Updated the default IAM token server URL.

- [FIXED] A performance regression deserializing JSON in version 2.10.1.

- [FIXED] Unexpected keyword argument errors when using the library w…

…ith the

 `simplejson` module present in the environment caused by `requests` preferentially
  loading it over the system `json` module.

- [NEW] Add custom JSON encoder/decoder option to `Document` construc…

…tor.

- [NEW] Add new view parameters, `stable` and `update`, as keyword arguments to `get_view_result`.
- [NEW] Allow arbitrary query parameters to be passed to custom changes filters.
- [FIXED] Case where an exception was raised after successful retry when using `doc.update_field`.
- [FIXED] Removed unnecessary request when retrieving a Result collection that is less than the `page_size` value.

- [NEW] Added functionality to test if a key is in a database as in `…

…key in db`, overriding dict `__contains__` and checking in the remote database.

- [NEW] Moved `create_query_index` and other query related methods to `CouchDatabase` as the `_index`/`_find` API is available in CouchDB 2.x.
- [NEW] Support IAM authentication in replication documents.
- [FIXED] Case where `Document` context manager would throw instead of creating a new document if no `_id` was provided.
- [IMPROVED] Added support for IAM API key in `cloudant_bluemix` method.
- [IMPROVED] Shortened length of client URLs by removing username and password.
- [IMPROVED] Verified library operation on Python 3.6.3.

- [FIXED] Installation failures of 2.8.0 caused by missing VERSION fi…

…le in distribution.

- [NEW] Added support for `/_search_disk_size` endpoint which retriev…

…es disk size information for a specific search index.

- [FIXED] Updated default IBM Cloud Identity and Access Management token URL.
- [REMOVED] Removed broken source and target parameters that constantly threw `AttributeError` when creating a replication document.

Merge pull request cloudant#336 from cloudant/prepare-2.7.0-release

Prepare for 2.7.0 release

2.6.0 (2017-08-10)

- [NEW] Added ``Cloudant.bluemix()`` class method to the Cloudant client allowing service credentials to be passed using the CloudFoundry VCAP_SERVICES environment variable.
- [FIXED] Fixed client construction in ``cloudant_bluemix`` context manager.
- [FIXED] Fixed validation for feed options to accept zero as a valid value.