automate publish with additional nexus plugins

[jpoehnelt]

This also gives us the option to close and release the staged version via cli in the future. ./gradlew tasks

Publishing tasks
----------------
generateMetadataFileForMapsJavaUtilsPublication - Generates the Gradle metadata file for publication 'MapsJavaUtils'.
generatePomFileForMapsJavaUtilsPublication - Generates the Maven POM file for publication 'MapsJavaUtils'.
publish - Publishes all publications produced by this project.
publishMapsJavaUtilsPublicationToMavenLocal - Publishes Maven publication 'MapsJavaUtils' to the local Maven repository.
publishMapsJavaUtilsPublicationToMavenRepository - Publishes Maven publication 'MapsJavaUtils' to Maven repository 'maven'.
publishMapsJavaUtilsPublicationToSonatypeRepository - Publishes Maven publication 'MapsJavaUtils' to Maven repository 'sonatype'.
publishToMavenLocal - Publishes all Maven publications produced by this project to the local Maven cache.
publishToSonatype - Publishes all Maven publications produced by this project to Nexus.

Release tasks
-------------
closeAndPromoteRepository - DEPRECATION WARNING. This task is DEPRECATED. Use 'closeAndReleaseRepository' instead.
closeAndReleaseRepository - Closes and releases an artifacts repository in Nexus
closeRepository - Closes an open artifacts repository in Nexus
createRepository - Internal task. Should not be used directly. Explicitly creates a staging repository in Nexus
getStagingProfile - Gets a staging profile id in Nexus - a diagnostic task
promoteRepository - DEPRECATION WARNING. This task is DEPRECATED. Use 'releaseRepository' instead.
releaseRepository - Releases a closed artifacts repository in Nexus

[coveralls]

Coverage remained the same at 74.017% when pulling 1faa5fb on publish_test into 538afb7 on master.

[amuramoto]

@jpoehnelt Can we hold this until the release of 0.10.2 or 0.11.0? Just to make sure everything works as expected for a live release before we merge this.

[jpoehnelt]

Can we hold this until the release of 0.10.2 or 0.11.0? Just to make sure everything works as expected for a live release before we merge this.

This only stages and runs when a git tag/release is created. It's still a manual process to close and release. What benefit is there in waiting?