JACOCO-86 Revert "JACOCO-88 Prepare next development iteration 1.5.1"

Revert to version 1.6.0-SNAPSHOT to ensure the greatest version number
being picked for deployment on Next corresponds to the latest build on
master.

This reverts commit 7bd9fa0.

Author: dorian-burihabwa-sonarsource

gradle.properties

@@ -1,4 +1,4 @@
 group=org.sonarsource.jacoco
-version=1.5.1-SNAPSHOT
+version=1.6.0-SNAPSHOT
 description=SonarQube plugin to import JaCoCo XML coverage reports
 projectTitle=SonarQube JaCoCo plugin