Major health check refactoring.

- Modified protocol buffer backing health checks
- Task health checks are now executed by short-lived, per-request actors
- Upgrades akka and spray library versions
Merge branch 'master' into wip-health-checks-refactored
Removed @Provides method for HealthCheckManager
Add healthCheckResults to the apps task resource
Merge pull request #217 from mattstep/wip-health-checks-refactored

Add healthCheckResults to the apps task resource
Rebase: master
Merge branch 'master' into wip-health-checks-refactored
HealthCheck primitives for new Jackson module
Issue #208: Allow relative paths to executor
The AppDefinition.executor property now has to hold a valid URI.
Add URI Annotation and validator.
Issue #165: Remove Content-Type from 204 responses
It is a jersey Bug: https://java.net/jira/browse/JERSEY-953
Should be fixed in Version 1.18.
Updated to latest 1.x version which is 1.18.1
The error remains the same.
Moved the class level annotation to every method and handle it explicitly.
jersey use transitive version of chaos
Use Try.isSuccess instead of map
-Thread MarathonSchedulerService is started, but not stopped when shut down is triggered
Enrich start script: allow parameter for the jvm, especially allow to attach a remote debugger
Log app ID when offers don't match
#222 Show apps with empty ports in endpoint api
-Add Test to ensure backward compatibility
Fix for #185: zookeeper config format different than mesos. necessary?
ZookeeperConf: deprecate zk_hosts and zk_state, introduce zk_marathon, introduce zk_URL, zkHosts and zkPath parameter as value holder
ZookeeperConfTest: create test case to ensure existing behaviour is still valid, add url parameter handling
MarathonModule: use zkHosts instead of old hostString
Merge pull request #224 from drexin/wip-222-return-tasks-with-empty-ports-drexin

#222 Show apps with empty ports in endpoint api
Update Readme.md to reflect parameter name changes.