View/download a list of buckets with custom (non-default) properties [JIRA: RIAK-1725]

[dmitrizagidulin]

Add ability to view (and download to a text file) the list of buckets with custom properties (ones that have search enabled, or custom N values, etc). (These are the ones currently stored in the ring files, gossiped around the cluster, etc). This is for use with logical cluster backup (so that users know which custom bucket properties to save).

For example, the Riak Data Migrator (https://github.com/basho/riak-data-migrator ) has the -t option to export/import custom bucket properties, which is currently the only way to back up that crucial information. The command requires a list of custom buckets, however, since there's currently no way to discover which buckets have non-standard settings. And currently, customers have to keep this list externally (basically, keep track of which buckets whose properties they modified, if they want those properties to persist through backup/restore operations).

This feature would make this process slightly easier. Additionally, seeing the list of custom buckets would serve as a useful red flag to devops (since a large number of custom buckets poses a serious performance risk to a Riak cluster).

[DSomogyi]

Comment for Jira.