Release Candidate 2

[2.0.0-rc.2] - 2019-06-03

Changes

• Now using golang standard context.Context instead of groupcache.Context.
• HTTP requests made by httpGetter now respect context.Context done.
• Moved HTTPPool config Context and Transport to HTTPPoolOptions for consist configuration.
• Now Associating the transport with peer httpGetter so we take advantage of
  connection reuse. This lowers the impact on DNS and improves performance for
  high request volume low latency applications.
• Now always populating the hotcache. A more complex algorithm is unnecessary
  when the LRU cache will ensure the most used values remain in the cache. The
  evict code ensures the hotcache does not overcrowd the maincache.
• Changed import paths to /v2 in accordance with go module rules