Allow dots in migration names

Added the dot (.) as an allowed character in database name regex.
Background: simple_roles gem creates migrations with names like
create_user_roles.simple_roles.rb. Health check was raising a
NoMethodError on such migration files.
Update test to handle migrations with dots and stop get_migration_version method crashing on weird migration names
Merge branch 'dots-in-migration-names'
Added thanks to contributers