Release Notes - Apache Twill - 0.6.0-incubating

New features:
[TWILL-116] Support for restart instances of runnable in an application
[TWILL-117] MapR extension
[TWILL-130] Remove support for Java 6

Improvements:
[TWILL-24]  log level should be settable
[TWILL-69]  Remove guava dependencies on the twill-api and twill-common modules
[TWILL-83]  distribute YarnTestUtils for easier downstream testing
[TWILL-112] Improve ApplicationBundler performance
[TWILL-126] Update Travis CI configuration to support caching Maven downloads
[TWILL-128] Change the ZKBrokerService to be public so it could be used outside the package
[TWILL-135] Update the pom.xml to get Java7 API link and update copyright year
[TWILL-137] Be able to get log level for each runnable via TwillController.getResourceReport

Bug fixes:
[TWILL-120] Java 8 applications causing exceptions
[TWILL-121] Do not know which class TwillLauncher was trying to launch
[TWILL-125] BundledJarRunner doesn't work for classes with no zero-args constructor
[TWILL-127] The link for API doc for 0.6 release returns 404
[TWILL-129] Race condition in leader election if leader quitted before follower set the watch
[TWILL-133] ZookeeperClientService may hang at startup and then cannot be stopped
[TWILL-136] Override equals and hashCode for JvmOptions.DebugOptions to test equality
[TWILL-139] ApplicationMaster hangs during start when ZooKeeper SASL authentication is turned on