Internal: split internal fetch request used within scroll and search

Similar to #7856 but relates to the fetch shard level requests. We currently use the same internal request when we need to fetch within search and scroll. The two original requests though diverged after #6933 as SearchRequest implements IndicesRequest while SearchScrollRequest doesn't. That said, with #7319 we made `FetchSearchRequest` implement IndicesRequest by making it hold the original indices taken from the original request, which are null if the fetch was originated by a search scroll, and that is why original indices are optional there.

This commit introduces a separate fetch request and transport action for scroll, which doesn't hold original indices. The new action is only used against nodes that expose it, the previous action name will be used for nodes older than 1.4.0.Beta1.

As a result, in 1.4 we have a new `indices:data/read/search[phase/fetch/id/scroll]` action that is equivalent to the previous `indices:data/read/search[phase/fetch/id]` whose request implements now IndicesRequest and holds the original indices coming from the original request. The original indices in the latter request can only be null during a rolling upgrade (already existing version checks make sure that serialization is bw compatible), when some nodes are still < 1.4.

Closes #7870
Docs: Replaced 1.4.0 tags with 1.4.0.Beta
Docs: Removed old added/coming/deprecated tags for pre 1.4 releases
Docs: Updated ES and JVM version replacements
Docs: Removed a reference to 1.5.0 changes
Docs: Moved breaking changes 1.x to 1.4
If a node is being shutdown some in flight ping request may be executed. Make sure to keep track of those ping requests and close the unicast connect executor service.

Closes #7903
Internal: MulticastChannel should wait on receiver thread to stop during shutdown

This was signaled by our tests which shutdown class and check for thread leakage.

Closes #7835
Update suggesters.asciidoc

A request was malformed

Closes #7867
GeoJSON is lon,lat

Although emphasized in the text, the example was backwards.

Closes #7843
Improve sentence structure

Closes #7842
Remove comma in JSON

Closes #7827
Fix Idaho spelling

Doesn't have two `d`s.

Closes #7802
Clarify s3 snapshot compress behavior

Clarify s3 snapshot compress behavior only applies to metadata and no index files.

Closes #7654
fix concurrency bug in index throttling
Core: upgrade to Lucene 4.10.1
fix typo: sonartype -> Sonatype
Refactor the Translog.read(Location) method

It was only used by `readSource`, it has been changed to return a
Translog.Operation, which can have .getSource() called on it to return
the source. `readSource` has been removed.

This also removes the checked IOException, any exception thrown is
unexpected and should throw a runtime exception.

Moves the ReleasableBytesStreamOutput allocation into the body of the
try-catch block so the lock can be released in the event of an exception
during allocation.
Discovery: master fault detection fall back to cluster state thread upon error

With #7834, we simplified ZenDiscovery by making it use the current cluster state for all it's decision. This had the side effect a node may start it's Master FD before the master  has fully processed that cluster state update that adds that node (or elects the master master). This is due to the fact that master FD is started when a node receives a cluster state from the master but the master it self may still be publishing to other node.

This commit makes sure that a master FD ping is only failed once we know that there is no current cluster state update in progress.

Closes #7908
Fix missing import