Consistent REST API changes for GETting data

* Made GET mappings consistent, supporting
  * /{index}/_mappings/{type}
  * /{index}/_mapping/{type}
  * /_mapping/{type}
  * Added "mappings" in the JSON response to align it with other responses
* Made GET warmers consistent, support /{index}/_warmers/{type} and /_warmer, /_warner/{name}
  as well as wildcards and _all notation
* Made GET aliases consistent, support /{index}/_aliases/{name} and /_alias, /_aliases/{name}
  as well as wildcards and _all notation
* Made GET settings consistent, added /{index}/_setting/{name}, /_settings/{name}
  as well as supportings wildcards in settings name
* Returning empty JSON instead of a 404, if a specific warmer/
  setting/alias/type is missing
* Added a ton of spec tests for all of the above
* Added a couple of more integration tests for several features

Relates #4071
Consistent APIs: Get field mapping API includes 'mappings'

The get field mapping API now includes a mappings element after the index in its JSON

Added more consistent endpoint /{index}/_mapping/{type}/field/{fields}
and added endpoint /_mapping/{type}/field/{fields}
which are also used in tests

Added rest spec tests for wildcards and _all

Relates #4071

NOTE: This is not yet complete for 1.0. We need to return an empty JSON document instead
of a 404 if the field of an existing index and type is not found. However this is not
possible with the current data structure being returned. Needs to be finished for 1.0.
Use most recent cluster state to find types in delete mapping

Previously, the cluster state before flushing was used to check which
types map the given types pattern. However, this state might not be
up to date. Instead use the more recent cluster state from clusterState.state()
This fixes a test failure of PercolatorTests.testDeletePercolatorType

Other changes:

- use BoolFilter instead of OrFilter, because it is faster
- throw exception immediately when no type matching the given patterns
  was found in cluster state
update rest spec to be consistent with recent changes

see issue #4071
[DOCS] Moved fielddata circuit breaker higher up the page
[DOCS] Tidied up cluster settings docs
Increased max map pages for systemd to align with init.d settings in packages
[DOCS] Fix default setting in circuit breaker documentation
[DOCS] Tidied up layout of setup docs