Introduce cache.memory_ratio configuration for HPCache

New set-and-forget configuration that specifies cache size as a ratio of the
old generation max size. Memory division across internal components of the cache
is handled by fixed ratios.

If any of the old config (now referred to as "advanced config") is set, it will
override the memory_ratio configuration.
Everything not starting with 'cmdchar' is cypher.

* Also remove old debug message
Improvements to the application pause monitor.

- Use System.nanoTime() to remove false-positive from network time adjustments
  and other external factors.
- Don't track total block time, It isn't a useful metric and it was confusing.
- Have the "trigger" level be the max block time that's acceptable, rather than
  the max block time plus the monitor pause interval.
- Bump the default block time trigger level to 200ms
- Introduce a manual mechanism to verify that the monitor works.
Merge pull request #3042 from oskarhane/send_all_but_commands_to_server

[2.0] Browser: Everything not starting with 'cmdchar' is cypher.
Merge pull request #2849 from jakewins/2.1-cache-config

[2.1] Introduce cache.memory_ratio configuration for HPCache
Merge pull request #3076 from jakewins/2.0-gc-logging

Improvements to the application pause monitor.
Merge branch '2.0-maint' into 2.1-maint

Conflicts:
	community/browser/app/scripts/init/commandInterpreters.coffee
Merge branch '2.1-maint'

Conflicts:
	community/kernel/src/test/java/org/neo4j/helpers/SettingsTest.java