PIP-823: Refactor and Improvements for v1.0.0

[thrawn01]

Purpose

To prepare for the 1.0.0 release. This PR changes the names of public methods and config options to provide a more consistent interface.

Config Changes

• Added GUBER_DATA_CENTER
• Use GUBER_PEER_DISCOVERY_TYPE to pick a peer discovery type
• Added GUBER_ADVERTISE_ADDRESS to specify which address is published for discovery
• Gubernator now attempts to detect the proper GUBER_ADVERTISE_ADDRESS if not specified
• Added DataCenter to member-list and etcd metadata

Implementation

• Added GUBER_DATA_CENTER as a config option
• Use GUBER_PEER_DISCOVERY_TYPE to pick a peer discovery type, removed
  'Enable' options from k8s, etcd, and member-list.
• Added GUBER_ADVERTISE_ADDRESS to specify which address is published for discovery
• Gubernator now attempts to detect the proper GUBER_ADVERTISE_ADDRESS if not specified
• Gubernator now binds to localhost by default instead of binding to 0.0.0.0:80 to avoid allowing
  access to a test version of gubernator from the network.
• Fix inconsistent tests failing TestLeakyBucket & TestTokenBucket fails occasionally. #57
• Fix GRPC/HTTP Gateway /v1/HealthCheck dials default EtcdAdvertiseAddress even though only kubernetess is configured. #50
• Renamed functions to ensure clarity of version
• Removed deprecated EtcdAdvertiseAddress config option
• Refactored configuration options
• member-list metadata no longer assumes the member-list address is the same
  as the gubernator advertise address.
• Now MD5 sums the peer address key when using replicated hash. This ensures
  better key distribution when using domain names or ip address that are very
  similar. (gubernator-1, gubernator-2, etc...)
• Now defaults to replicated-hash if GUBER_PEER_PICKER is unset
• Added support for DataCenter fields when using etcd discovery
• Refactored cluster package to so we can test the full daemon instead of an isolated instance of Gubernator.
• Now storing member-list metadata as JSON instead of glob

[nipak]

Any update on merging this?

[thrawn01]

I've not forgotten about this! I have other priorities currently so I might be a challenge to find time to finish this month, if anyone is interested in rebasing this work and continuing It in a different branch, It would be most appreciated.