Consistent use of identity comparison (`is`/`is not`) for None
Bugfix: Removing a line that shouldn't have been brought back in during merge
Dyanamo Table.scan() should accept 'attributes' argument
Merge remote-tracking branch 'upstream/develop' into consistent-identity-comparison-none

Conflicts:
	boto/manage/server.py
download_to_fileobj() implementation per boto/boto#1941
Unit tests for new methods added in boto/boto#1960
Clarifying documentation for CloudWatchConnection.list_metrics().

- Multiple values for the same dimension are not supported by the API
- Max 10 dimensions allowed
Require a string value to instantiate Binary DynamoDB type

Prevents incorrect usage which results in potentially confusing errors.
Fixes #1956.
Added Autoscale Tag class to API docs
Merge pull request #1962 from oxtopus/documentation-fix-for-list_metrics

Clarifying documentation for CloudWatchConnection.list_metrics(). Fixes #1962.
Merge pull request #1964 from micahhausler/develop

Added Autoscale Tag class to API docs. Fixes #1964.
Fixed to no longer duplicate issues in release notes.
Merge pull request #1960 from oxtopus/issue-1941-download_to_fileobj

Glacier download_to_fileobj implementation. Fixes #1960.
Set security token via environment or config file

Support AWS_SECURITY_TOKEN environment variable and
aws_security_token in the config file.  Unit tests and doc change
included.  Ignored updating core/ as I assume core is abandoned in
favor of the separate botocore project.
Add support for arbitrary dict inputs to MWS calls
PEP8
Add unit tests for instantiating the DynamoDB Binary type.
Merge pull request #1963 from danielgtaylor/ddb-binary

Require a string value to instantiate Binary DynamoDB type. Fixes #1963, #1956.
Merge branch 'rn-issue-dupe-fix' into develop
Fixes #1965
Altered cert failure checks for regions.

This should make the integration tests happier.
Merge pull request #1930 from oxtopus/consistent-identity-comparison-none

Consistent use of identity comparison (`is`/`is not`) for None. Fixes #1930.