Update git submodules
Update git submodules

* Update plugins/cookbook-plugin from branch 'master'
  - Get rid of dependency on Guava
    
    Since I789f9aa589 removed usage of Guava's Optional, we only have
    the dependency on Guava for the following simple utility methods:
    
      Strings.isNullOrEmpty
      MoreObjects.firstNonNull
    
    Remove the dependency and instead provide own implementations
    of those methods.
    
    Change-Id: Iddcc20005004d37dae703fc0522c546a5212575c
    
WANdisco/gerrit,gerrit-review/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,gerrit-review/gerrit,GerritCodeReview/gerrit,gerrit-review/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,gerrit-review/gerrit,gerrit-review/gerrit,gerrit-review/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,gerrit-review/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit