[TEST] Improved IndexAliasesTests

more assertAcked, removed TODO and needless sleep
Improved CreateIndexRequest and CreateIndexRequestBuilder javadocs
[TEST] Added REST tests for create index api
Add missing PHRASE flag for simple_query_string

Closes #4911
Percolator response now always returns the `matches` key.

Closes #4881
[DOCS] unified index settings info and added warmers section in create index docs
Changed GeoEncodingTests to ensure accuracy always >1mm due to rounding errors with very small numbers
REST API: Consistent get field mapping response

If a get field mapping request is issued, and all but the field can be
found, the response should return an empty JSON object instead of a 404.

Closes #4738