Added console print option.
More cleanup.
Abandoned the idea of a plugin extension.
Renamed 'classpath' to 'checkstyleClasspath' for consistency with gradle source (https://github.com/kevinyang0906/gradle/blob/d6b37c30d1943a526e4885cdd43dd44caab56af3/subprojects/code-quality/src/main/groovy/org/gradle/api/plugins/quality/Checkstyle.groovy)
Removed unused extra property.
Formatted linespace.
Added PMD plugin for android.