Merges 2.0-maint into master

Conflicts:
  community/kernel/src/main/java/org/neo4j/kernel/impl/nioneo/xa/NeoStoreTransaction.java
Introduce per-version QueryCache

o This avoids allocating pairs of (version, query)
o This avoids allocating lambdas in prepare for compiler-2.1
Merge pull request #2007 from digitalstain/master

Merges 2.0-maint into master
Updates changelogs for 2.1.0-M01
Merge pull request #2010 from boggle/2.1-query-cache

Introduce per-version QueryCache
Merge pull request #2011 from davidegrohmann/2.1-doc-cleanup

2.1 cypher documentation test cleanup
Documentation for USING PERIODIC COMMIT clause
Documenting limitations of USING PERIODIC COMMIT in transactional endpoint