[zookeeper] Migrate ZK duties to Curator

[zookeeper] Finish migration to Curator and add tests

[zookeeper] Fix borked rebase

Conflicts:
	pom.xml
Fix for dependency invocation handling, tests.

This fixes 2 things:
 - don't try to restore invocation counts from ZK state (as they may be
   wrong due to missed status updates).
 - reset the invocation counts any time a dependent job starts.

Also added more tests around dependencies.

Conflicts:
	pom.xml
Exclude netty (from ZK) in pom.xml.
Fixed merge.
Fix http port 80 issue.
Upgrade to Mesos 0.18.2

* Mesos 0.18.2
* Chaos 0.5.6
* Scala 2.10.4
Remove email message for jobs that will be retried
Unify notification prefix on "[Chronos]"
Merge pull request #221 from mesosphere/mesos-0.18

Upgrade to Mesos 0.18.2
[chronos-sync] Permit .yaml or .yml suffix.
Merge pull request #225 from airbnb/notification-changes

Notification changes
Add mvn dependency:tree as before_script entry to aid debugging.
Set explicit script element
Disable travis' default mvn install
Remove before_script
fixed logging link in readme
Added validation for chronos-sync.
[chronos-sync] Improve logging.
Prefer offers with reserved resources, first.
Update the job correctly when disabled.