Backport bug fixes/improvements to opendistro-1.1

[dbbaughe]

Issue #, if available:

Description of changes:
Backports bug fixes and other improvements to 1.1

./gradlew build

Configure project :
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Elasticsearch Build Hamster says Hello!
Gradle Version : 5.4.1
OS Info : Mac OS X 10.12.6 (x86_64)
JDK Version : 12 (Oracle Corporation 12.0.2 [Java HotSpot(TM) 64-Bit Server VM 12.0.2+10])
JAVA_HOME : /Library/Java/JavaVirtualMachines/jdk-12.0.2.jdk/Contents/Home
Random Testing Seed : B72EC747E78E10F7
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Task :ktlint
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.jetbrains.kotlin.com.intellij.openapi.util.JDOMUtil$2 (file:/Users/dbbaughe/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-compiler-embeddable/1.3.31/965ef6d9abe1555cc5d0a34dd24ce93b49123e7c/kotlin-compiler-embeddable-1.3.31.jar) to constructor com.sun.xml.internal.stream.XMLInputFactoryImpl()
WARNING: Please consider reporting this to the maintainers of org.jetbrains.kotlin.com.intellij.openapi.util.JDOMUtil$2
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

Deprecated Gradle features were used in this build, making it incompatible with Gradle 6.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/5.4.1/userguide/command_line_interface.html#sec:command_line_warnings

BUILD SUCCESSFUL in 6m 47s
38 actionable tasks: 24 executed, 14 up-to-date

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.