AGP 3.0.1 compatibility

[TWiStErRob]

These tests fail on CI: AGP 3.0.1 on Gradle 4.2.1.

net.twisterrob.gradle.checkstyle.CheckStyleTaskTest_ConfigLocation.uses rootProject checkstyle config as a fallback()
net.twisterrob.gradle.checkstyle.CheckStyleTaskTest_ConfigLocation.uses local module checkstyle config over rootProject checkstyle config()
net.twisterrob.gradle.checkstyle.CheckStyleTaskTest_ConfigLocation.uses local module checkstyle config if available()
net.twisterrob.gradle.quality.tasks.HtmlReportTaskTest.task is re-executed when lint results are changed()
net.twisterrob.gradle.quality.tasks.HtmlReportTaskTest.runs on lints()
net.twisterrob.gradle.quality.tasks.HtmlReportTaskTest.runs on empty project()
net.twisterrob.gradle.quality.tasks.HtmlReportTaskTest.clean task removes output()
net.twisterrob.gradle.quality.tasks.HtmlReportTaskTest.task can be cleaned to force re-run()
net.twisterrob.gradle.quality.tasks.HtmlReportTaskTest.task is up-to-date when lint results are unchanged()
net.twisterrob.gradle.checkstyle.CheckStylePluginTest.custom source sets folders are picked up()
net.twisterrob.gradle.checkstyle.CheckStylePluginTest.applies to individual subprojects()
net.twisterrob.gradle.checkstyle.CheckStylePluginTest.applies to all types of subprojects()
net.twisterrob.gradle.checkstyle.CheckStylePluginTest.applies without a hitch to an Android project()
net.twisterrob.gradle.checkstyle.CheckStylePluginTest.applies to subprojects from root()
net.twisterrob.gradle.checkstyle.CheckStylePluginTest.basedir truncates folder names()
net.twisterrob.gradle.checkstyle.CheckStylePluginTest.exclusions are configurable per variant()
net.twisterrob.gradle.checkstyle.CheckStylePluginTest.config_loc allows to use local files()
net.twisterrob.gradle.quality.tasks.ValidateViolationsTaskTest.task is re-executed when violation results are changed()
net.twisterrob.gradle.quality.tasks.ValidateViolationsTaskTest.gather unique lint violations when multiple variants are linted()
net.twisterrob.gradle.quality.tasks.ValidateViolationsTaskTest.get total violation counts on root project()
net.twisterrob.gradle.quality.tasks.ValidateViolationsTaskTest.get total violation counts()
net.twisterrob.gradle.quality.tasks.ValidateViolationsTaskTest.get per module violation counts()
net.twisterrob.gradle.quality.tasks.ValidateViolationsTaskTest.do not gather non-existent reports()
net.twisterrob.gradle.quality.tasks.ValidateViolationsTaskTest.gather lint report when lintOptions-xmlOutput is set()

[TWiStErRob]

Obsolete, #369. Removed in #377