EMR: Bug fix in install-applications and create-cluster

1. Rename --apps to --applications in install-applications
2. Fixed bug in create-cluster --applications Name=MapR where Args is required.
EMR: Add unit tests for application
EMR: Update create-default-roles and Add --service-role & --use-default-roles
Test failure fix
Update changelog with latest changes
Bumping version to 1.3.19
Merge branch 'release-1.3.19' into develop

* release-1.3.19:
  Bumping version to 1.3.19
  Update changelog with latest changes
  Test failure fix
  EMR: Update create-default-roles and Add --service-role & --use-default-roles
  EMR: Add unit tests for application
  EMR: Bug fix in install-applications and create-cluster