Prometheus 2.0 Alpha.3 with New Rule Format

Prometheus 2.0 Alpha.3 introduces a new rule format using YAML, allowing for rule grouping with custom evaluation intervals and sequential execution to address performance and data dependency issues. This release also shifts to a double-dash `--` prefix for command-line flags and removes several older flags, requiring updates to existing deployments and configurations. A `promtool` command is provided to help migrate existing rules to the new YAML format.