Fixes #3734: Rename SuSE to SUSE and keep SuSE* classes for backwards compatibility
Add deprecated tag to all SuSE class definitions
Clarify deprecation duration in comments, and fix sys.flavo[u]r to use SUSE not SuSE
Clarify comments about deprecating SuSE vs SUSE class names
Add Changelog message about SUSE name change.
Merge branch 'rename_SuSE_to_SUSE_redmine_3734'