+++ This bug was initially created as a clone of Bug #1576842 +++

Description of problem:

Currently, the plugins are not configurable.

Expected results:

Plugins should be configurable.

--- Additional comment from Worker Ant on 2018-05-10 19:04:19 MVT ---

REVIEW: https://review.gluster.org/20000 (features/cloudsync: Make plugins configurable) posted (#3) for review on master by Susant Palai

--- Additional comment from Worker Ant on 2018-05-22 12:49:07 MVT ---

COMMIT: https://review.gluster.org/20000 committed in master by "Amar Tumballi" <amarts> with a commit message- features/cloudsync: Make plugins configurable

This patch brings the configuration option for plugins.

For new plugins, an entry has to be created in to cs_plugin structure e.g.
struct cs_plugin plugins[] = {
        {
          .name = "amazons3",
          .library = "libamazons3.so",
          .description = "amazon s3 store."
        },

        {.name = NULL},
};

Library field describes the name of the shared library for the plugin.

To configure plugin type "feature.cloudsync-storetype" option need
to be set to the remote-store type. e.g.

gluster volume set VOLNAME cloudsync-storetype amazons3. This should be same
as the ".name" field in cs_plugin structure.

cs_init will pick this up in run time to load the plugin.

Change-Id: I2cec10b206f71ac4e71d472631a3a5badf278b59
fixes: bz#1576842
Signed-off-by: Susant Palai <spalai>