Adds Gradle release plugin.
Now records project version number in gradle.properties instead of build file.
Adds .gitignore file.
Configures plugin publication based on Gradleware recommendations. Change plugin to com.github.gmazelier.jasperreports.
Fixes tests. Packages now match plugin id.
Adds installation instructions.
Adds Java 1.6 compatibilty on Groovy compilation.
Adds main usage description.
Adds Bintray link.