Update Elasticsearch to 7.x

[Daniel Zoller]

Here are some warnings while running with 6.8.1:

• The [standard] token filter is deprecated and will be removed in a future version.
• the default number of shards will change from [5] to [1] in 7.0.0; if you wish to continue using the default of [5] shards, you must manage this on the create index request or with an index template