[chronos-sync] Validate fields, use defaults.

The required fields should be validated, and we should set a default for
some optional fields (only `highPriority` at this point).
Adding bridge-mode support to docker containers
JobStats: catch exception on C* failures.

When trying to create a C* session, we must be sure to handle exceptions
appropriately, rather than exploding.
Merge pull request #295 from airbnb/fix-bad-exception-handling

JobStats: catch exception on C* failures.
Fix tutorial link
Merge pull request #292 from sdwr98/bridge-mode

Adding brigde mode support for docker containers
Merge pull request #297 from jamesgary/master

Fix tutorial link
Adding support for Mesos shell and arguments parameters to CommandInfo
Merge pull request #282 from sdwr98/shell-param

Adding support for Mesos shell and arguments parameters to CommandInfo
Committing suicide if mesos registration fails - this allows leadership transfer
added log message
Using string interpolation to adhere to scala style guidelines
Merge pull request #298 from airbnb/registration_failure_suicide

Committing suicide if mesos registration fails - this allows leadership ...
better help for mail server option
Merge pull request #299 from Topface/mail-server-help

Better help for mail server option
Clear job graph when no longer leader.

When re-elected, Chronos attempts to re-create the job graph; this
patch prevents doing so with vertexes that are already in the job
graph, which is an illegal operation.
Adding softError property to Job entity

It will be used to control whether a job failure should or should not short circuit it's dependency graph.
Merge pull request #300 from DevOps-TangoMe/master

Clear job graph when no longer leader.
Don't schedule queued jobs if they have been disabled
Remove a meaningless function invoking

Invoking skipForwad is not needed if job.schedule cannot be parsed.
So it is meaningless to parse it twice.