Additions and enhancements (#14)

- add interactive API repl
- enhance cluster status output (use -v)
- add more ccr commands
- refactoring

TODO.md

@@ -2,6 +2,6 @@
 - [ES API docs](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-get)
 
 - Fix index names custom completion
-- add cluster default <name> which would add a flag to the config, so that no -C is needed subsequently
-- add `cluster stats` from `/_cluster/stats` like mem, procs, open files, num indices, shards etc
-  or add these to `cluster status`, maybe add a `--stats` to include stats there?
+- index show: add more details, see screenshots
+- add shard explain, aka:
+  get /_cluster/allocation/explain {"index":"yourindex", "primary": true, "shard":0}