* Update elasticsearch_plugin.py
Change module to work with Elasticsearch 2.x and 5.x automatically.
Update examples and docs.
Supersedes #21989
* Check system paths for elasticsearch-plugin binary
Use get_bin_path from basic.py for searching paths.
* Create a copy of PLUGIN_BIN_PATHS rather than modifying the global
* Use provided plugin_bin path first before trying other places
Change global PLUGIN_BIN_PATHS to a tuple
a5ee865634