public final void execute()
Called when the Maven plug-in is executing. It creates an in-memory ZIP file of all the Chrome Extension
source files, generates as signature using the private key from the PEM file, outputs a CRX file containing
a header, the public key, the signature and the ZIP data.
org.apache.maven.plugin.MojoExecutionException - If there was an error that should stop the build.
org.apache.maven.plugin.MojoFailureException - If there was an error but the build might be allowed to continue.