Abbreviate common connection closed error.

When the client closes a connection to the server before recieving the full
reply, the server currently prints a lengthy stack trace to the log. This
stack trace is not helpful, because we already do the right thing here.

Replace stack trace with one-line log message noting the client closed the
connection.
Merge pull request #3392 from lutovich/merge-2.0-to-2.1

(2.0)-[:MERGE]->(2.1)
Introduce debug capability for request content logging.

Currently undocumented, this introduces experimental support for logging
full request and response bodies. This is currently enabled by setting:

    org.neo4j.server.http.unsafe.content_log.enabled=true

In neo4j-server.properties, and by specifying the http log to output full
requests and responses:

    <pattern>%fullRequest\n\n%fullResponse</pattern>

As this uses mechanisms to fully duplicate incoming request and response
streams, it is strongly recommended to not run this in a production setting.
However, it should prove very useful for debugging and testing.
Fix flay testserverbuilder test.
Merge pull request #3377 from jakewins/2.1-connmsg

Abbreviate common connection closed error.
Merge pull request #3399 from chrisvest/2.1-req-content-logging

Introduce debug capability for request content logging.
Fix bug in EphemeralFileSystem

When you write beyond the end of a file, the space in between is filled with zeros.
The EphemeralFileSystemAbstraction had insufficient synchronisation in that code, because it allowed
a thread to do a write beyond the end of the file, then another thread would write in the space in
between, and then the first thread would overwrite the new data with zeros.

During the course of debugging this, the PageCacheMonitor has been extended to also observe page
flushes.

Conflicts:
	community/io/src/main/java/org/neo4j/io/pagecache/PageCacheMonitor.java
	community/io/src/main/java/org/neo4j/io/pagecache/impl/common/SingleFilePageSwapper.java
	community/io/src/main/java/org/neo4j/io/pagecache/impl/standard/ClockSweepPageTable.java
	community/io/src/main/java/org/neo4j/io/pagecache/impl/standard/StandardPinnablePage.java
	community/io/src/test/java/org/neo4j/io/pagecache/CountingPageCacheMonitor.java
	community/io/src/test/java/org/neo4j/io/pagecache/PageCacheTest.java
	community/io/src/test/java/org/neo4j/io/pagecache/RecordingPageCacheMonitor.java
	enterprise/enterprise-io/src/main/java/org/neo4j/io/enterprise/pagecache/impl/muninn/MuninnPage.java
	enterprise/enterprise-io/src/main/java/org/neo4j/io/enterprise/pagecache/impl/muninn/MuninnPagedFile.java
Expose Node degree in REST API.
Merge pull request #3395 from jakewins/2.1-testserverbuilder-flakyness

Fix flay testserverbuilder test.
Swap forseti clients over to using primitive maps.

Replace Forseti clients usage of regular hashmaps with hopscotch primitive
maps for tracking local lock counts. This makes a large section of the forseti
hot path GC free.

Also includes the optimization from RecordChanges where we allocate a new map
if the existing map has gotten larger than 32 entries.
Merge pull request #3404 from chrisvest/2.1-ephemeral-fsa-threadsafe-backport

Fix bug in EphemeralFileSystem
Merge pull request #3408 from jakewins/2.1-forseti-gc

Swap forseti clients over to using primitive maps.
Separate boss and worker executors in Client
Activate Grunt rev task

- Prepends js and css file names with md5 of
contents so web browsers don't load cached files
when the contents has changed.
Make more extensive request metadata available in batch requests.
Merge pull request #3412 from lutovich/1.9-flaky-TestCommunication

Separate boss and worker executors in Client
Merge remote-tracking branch 'upstream/1.9-maint' into 2.0-maint

Conflicts:
	enterprise/com/src/main/java/org/neo4j/com/Client.java
Merge branch '2.0-maint' into 2.1-maint
Merge pull request #3405 from jakewins/2.1-batchfix

Make more extensive request metadata available in batch requests.
Remove conflicting dependencies.