Set longer timeout when waiting for sonatype

We've gotten timeouts when waiting for sonatype to perform
the release operation. Let's change it to 10 minutes from
the default of 5 minutes. Also bump to the latest version.
Fix NPE thrown by Optional

Need to call 'fromNullable' instead of 'of'
Merge pull request #306 from spotify/rculbertson/npe

Fix NPE thrown by Optional
Merge pull request #305 from spotify/rculbertson/nexus-timeout

Set longer timeout when waiting for sonatype
Fix SyslogRedirectionTest

Wait for container to exit to ensure cmd was run
and logs aren't empty which causes the test to fail.
Merge pull request #307 from spotify/dxia/fix-SyslogRedirectionTes

Fix SyslogRedirectionTest
Test that we can deploy a large number of jobs

Deploy 40 jobs, kill all the underlying containers, and make sure the
system recovers.
Merge pull request #308 from spotify/rohan/concurrent

Test that we can deploy a large number of jobs
Improve helios host output message

Clarify a comment and remove a TODO

Fixes #304
Merge pull request #309 from spotify/dxia/better-host-msg

Improve helios host output message
Upgrade docker-client dep to 2.7.3
Merge pull request #310 from spotify/dxia/upgrade-docker-client

Upgrade docker-client dep to 2.7.3