Change neo4j-community packaging from jar to pom.
Turn PageCache.unmap into PagedFile.close
Fix a couple of warnings in PageCacheTest
Fix page cache bug where write cursors racing with PagedFile.close can prevent dirty pages from being flushed to storage
EncodingIdMapper: At least one processor.
Merge pull request #3719 from martinfurmanski/2.2-encoding-id-mapper-min-proc

EncodingIdMapper: At least one processor.
Supports multiple disjoint id spaces within the same IdMapper

Each id given to IdMapper is accompanied a Group with an id. Looking up a
value in the IdMapper requires to pass a predicate for matching ids.

Currently this functionality isn't yet used by Input implementations, but
that can be viewed as a separate concern, where this commit is just for
enabling the feature.
Merge pull request #3709 from nawroth/neo4j-community-pomfix

Change neo4j-community packaging from jar to pom.
Merge pull request #3703 from chrisvest/2.2-unmap-to-close

Turn PageCache.unmap into PagedFile.close
Merge pull request #3686 from tinwelint/2.2-disjoint-id-spaces

Supports multiple disjoint id spaces within the same IdMapper
Revert "Disable varlength planning in Ronja and fallback to the legacy planner"

This reverts commit 090c8775e53a0edf413b891827cb610269bd8f93.

Conflicts:
	community/cypher/cypher-compiler-2.2/src/main/scala/org/neo4j/cypher/internal/compiler/v2_2/planner/logical/expandsOrJoins.scala
	community/cypher/cypher/src/test/scala/org/neo4j/cypher/MatchAcceptanceTest.scala
Decouple compiler version and planner version

To control language version `CYPHER x.y` and to control
planner we have
```
PLANNER COST
PLANNER RULE
```
By default we use a variant that uses what we currently is known to be safe in COST and
fallback to RULE when we are at risk of creating slow plans. Currently we don't do varlength,
cycles and updates in COST.

The default planner can also be configured by `query.planner.version`.