Sceptre

- Changing syntax used for resolvers and hooks in config files.
- Deprecating use of `sceptre_get_template` function in Troposphere templates.
- Deprecating the accessing of Troposphere templates returned from
`sceptre_get_template`.
- Deprecating the accessing of Troposphere templates from the global variable
`t`.
- Deprecating the global variable `SCEPTRE_USER_DATA`.
- Adding support for `sceptre_handler` function in Troposphere templates.
- Adding support for pure CloudFormation JSON strings returned by
`sceptre_handler`.
- Adding support for `sceptre_user_data` passed to `sceptre_handler`.
- Fixing bug in update-stack-cs.
- Adding project-variables resolver.

- Adding documentation for CloudFormation Service Role.

- Updating documentation on hooks.
- Adding support for CloudFormation Service Role.
- Adding support for custom stack names.
- Removing (before|after)\_launch hook.
- Changing documentation styling.
- Adding Python 3 support.
- Adding --verbose argument to describe-change-set.
- Adding support for launching stacks without uploading the template to S3.
- Adding a FAQ section on `parameters` vs `sceptre_user_data`.
- Adding support for CloudFormation template written in YAML.
- Bumping boto3 requirement.
- Adding more intuitive delete stack message.
- Removing profile.
- Fixing a multithreading bug.
- Improve CLI UX by printing only an exception's message, not the whole stack
trace.
- Adding environment path check.
- Refactoring out code that fetches stack status.

- Fixing StackStatusColourer: UPDATE_FAILED wan't coloured.
- Fixing bug from uploading templates to S3 from Windows.
- Improving exception thrown when a user tries to use the stack output resolve
on a stack with no outputs.

- Launch now deletes stacks in the CREATE_FAILED or ROLLBACK_COMPLETE states
before re-creating them.
- Adding support for Troposphere<1.10.0.

- Adding support for multiple environments.
- Speeding up integration tests.
- Switching to CircleCI for continuous integration and deployment of
documentation.
- Changing template S3 key to use a UTC timestamp rather than seconds since
epoch.
- Changing update-stack-cs to delete the change set by default.
- Stopping appending region to template bucket name.
- Refactoring logger.
- Changing exception names from <Name>Exception to <Name>Error.
- Publishing development docs to http://sceptre-dev.ce-tools.cloudreach.com/.