cypher performance enhancements

rewrote pathimpl
replaced Iterator() with Iterator.empty
replaced List() with List.empty
replaced Seq() with Nil
replaced seq.size with alternative predicates
cypher performance part2

especially around paths
taking collection types into account
taking PathImpl into account
using Array to build up the node and rel collections in PathImpl
using collections.mutable.OpenHashMap in MutableMaps
Merge pull request #654 from jexp/cypher-performance

cypher performance enhancements
Enables lists of maps in gremlin

Fixes this issue: https://github.com/neo4j-contrib/gremlin-plugin/issues/7
Temporarily ignore test in HaBeanIT pending investigation
Removes duplicate test that was also causing expected failures
Shuts down cluster manager in BackupHaIT, tries to fix port in use errors
Moves ForeignStoreIdIT from default interface to localhost
recovered missing branding; softened colors in CSS; completed tour, learn, and develop guides

collapsed participate and read into explore guide, with pages for community, videos, and books

changed group photo

tweaks to font sizing, based on media query for typical projector size

improved media queries for 3 sizes of guide; still issues with ie9

improved responsive layout on ie9

revised connection lost to use show/hide instead of add/remove
Changes port in ForeignStoreIdIT to work around conflicts in CI
upgraded netty and refactored netty resource management
Merge pull request #674 from akollegger/guide

Replace splash screen with built-in guide
Updated the system requirements.
Removes extra slash from path for HA REST info resource
Makes key naming consistent with resource name
Turn off NetworkInstance debug, so that a running instance with no load does not generate any messages in messages.log
Remove high cluster join timeout in cluster tests
Makes cluster tests more scheduling insensitive by removing concurrent startups of clusters
Increases interval in cluster test
Merge remote-tracking branch 'upstream/master' into netty363
Fixes issue where batch insertion on existing db would delete indexes

When doing batch insertion on an existing database containing indexes,
those indexes, or rather the configuration for them (as well as the
existence of them from the dbs POV) would be deleted if not used in this
second batch insertion. I.e. any index configuration would be overwritten
with whatever this second batch insertion did.

Problem being that the existing index configuration wasn't read (the call
to indexStore.start()) so when shutting down in the end and writing the
index configuration, any existing would be lost.

Fixes #527