Cloudant

- [FIXED] Unexpected keyword argument errors when using the library with 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` constructor.
- [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 file in distribution.

- [NEW] Added support for `/_search_disk_size` endpoint which retrieves 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.

- [NEW] Added API for upcoming Bluemix Identity and Access Management support for Cloudant on
Bluemix. Note: IAM API key support is not yet enabled in the service.
- [NEW] Added HTTP basic authentication support.
- [NEW] Added `Result.all()` convenience method.
- [NEW] Allow `service_name` to be specified when instantiating from a Bluemix VCAP_SERVICES
environment variable.
- [IMPROVED] Updated `posixpath.join` references to use `'/'.join` when concatenating URL parts.
- [IMPROVED] Updated documentation by replacing deprecated Cloudant links with the latest Bluemix
links.