1: Added capability for user to specify truststoreFile, truststorePass and clientAuth settings in order to configure Tomcat for client certificate (x.509) usage.
2: Added appropriate tests in TomcatRunTest.groovy for new functionality
3: Slightly refactored some validation in AbstractTomcatRunTask to allow me to adhere to DRY principle whilst adding validation for the new configurable attributes
4: Updated README.md to document the new functionality