fix logging message to include the index
also add the list of current indices
use ImmutableList.Builder instead of ArrayList
make ES compile with java 8
- that isAnnotationPresent bug is known, and probably will be fixed in later versions, but it costs us nothing to not use it now
- some tests fail, mainly due to consistent ordering expected from Map (within versions) which does not seem to be preserved, need to fix those tests to be agnostic to it
Field Data: optimize long type to use narrowest possible type automatically
closes #2795
List of existing plugins with Node Info API
We want to display information about loaded plugins in Node Info API using plugin option:

```sh
curl http://localhost:9200/_nodes?plugin=true
```

For example, on a 4 nodes cluster, it could provide the following output:

```javascript
{
  "ok" : true,
  "cluster_name" : "test-cluster-MacBook-Air-de-David.local",
  "nodes" : {
    "lodYfbFTRnmwE6rjWGGyQQ" : {
      "name" : "node1",
      "transport_address" : "inet[/172.18.58.139:9300]",
      "hostname" : "MacBook-Air-de-David.local",
      "version" : "0.90.0.Beta2-SNAPSHOT",
      "http_address" : "inet[/172.18.58.139:9200]",
      "plugins" : [ ]
    },
    "hJLXmY_NTrCytiIMbX4_1g" : {
      "name" : "node4",
      "transport_address" : "inet[/172.18.58.139:9303]",
      "hostname" : "MacBook-Air-de-David.local",
      "version" : "0.90.0.Beta2-SNAPSHOT",
      "http_address" : "inet[/172.18.58.139:9203]",
      "plugins" : [ {
        "name" : "test-plugin",
        "description" : "test-plugin description",
        "site" : true,
        "jvm" : false
      }, {
        "name" : "test-no-version-plugin",
        "description" : "test-no-version-plugin description",
        "site" : true,
        "jvm" : false
      }, {
        "name" : "dummy",
        "description" : "No description found for dummy.",
        "url" : "/_plugin/dummy/",
        "site" : false,
        "jvm" : true
      } ]
    },
    "bnoySsBfTrSzbDRZ0BFHvg" : {
      "name" : "node2",
      "transport_address" : "inet[/172.18.58.139:9301]",
      "hostname" : "MacBook-Air-de-David.local",
      "version" : "0.90.0.Beta2-SNAPSHOT",
      "http_address" : "inet[/172.18.58.139:9201]",
      "plugins" : [ {
        "name" : "dummy",
        "description" : "This is a description for a dummy test site plugin.",
        "url" : "/_plugin/dummy/",
        "site" : false,
        "jvm" : true
      } ]
    },
    "0Vwil01LSfK9YgRrMce3Ug" : {
      "name" : "node3",
      "transport_address" : "inet[/172.18.58.139:9302]",
      "hostname" : "MacBook-Air-de-David.local",
      "version" : "0.90.0.Beta2-SNAPSHOT",
      "http_address" : "inet[/172.18.58.139:9202]",
      "plugins" : [ {
        "name" : "test-plugin",
        "description" : "test-plugin description",
        "site" : true,
        "jvm" : false
      } ]
    }
  }
}
```

Information are cached for 10 seconds by default. Modify `plugins.info_refresh_interval` property if needed.
Setting `plugins.info_refresh_interval` to `-1` will cause infinite caching.
Setting `plugins.info_refresh_interval` to `0` will disable caching.

Closes #2668.