on-board knn plugin to odfe-cli

[VijayanB]

Add knn plugin to odfe-cli.
Example:

Usage:
  odfe-cli knn [command]

Available Commands:
  stats       Status of KNN Plugin
  warmup      Warmup shards for given indices

Flags:
  -h, --help   Help for k-NN plugin

Global Flags:
  -c, --config string    Configuration file for odfe-cli, default is /Users/balasvij/.odfe-cli/config.yaml
  -p, --profile string   Use a specific profile from your configuration file

Use "odfe-cli knn [command] --help" for more information about a command.

Owners: @VijayanB @vamshin @jmazanec15

[VijayanB]

PR is merged. This will be available in next release!