Schemachange

Changed
- Renamed snowchange to schemachange
- Please be advised that the new default path for the change history table is now `METADATA.SCHEMACHANGE.CHANGE_HISTORY` (the schema name has been changed from `SNOWCHANGE` to `SCHEMACHANGE`). The easiest thing to do is rename the metadata schema in Snowflake. The other option is to leave it as is and use the `--change-history-table` (or `-c`) parameter to override the default.

Added
- Added a new optional parameter `--dry-run` to preview scripts that will be applied by snowchange.

Added
- Added a Snowflake query tag to all snowchange queries. If the query is issued by the tool the tag will be "snowchange .." (e.g. "snowchange 2.7.0") and if the query is part of a change script the tag will be "snowchange ..;<script name>" (e.g. "snowchange 2.7.0;V1.1.1__initial_database_objects.sql")

Added
- Added a new optional parameter `-d` or `--snowflake-database` to specify the default database to use (which can always be overridden in an individual change script)
- Added a new optional parameter `--create-change-history-table` to create the change history table if it does not exist

Changed
- The default mode of operation now is to not create the change history table if it doesn't exist. Instead, now if the history table doesn't exist the tool will fail by default.
- Added a check to see if the change history table exists before trying to create it, which is now also dependent upon the `--create-change-history-table` command line argument.
- Cleaned up command line argument descriptions

Removed
- Removed the ability for snowchange to create the database for the change history table. snowchange now requires the database to be created ahead of time.

Added
- Support for encrypted key pair authentication

Added
- PyPI package support so that snowchange can be installed through pip
- Dockerfile for building Docker images

Changed
- Allow for .SQL file extensions (common in Windows environments) in addition to .sql extensions