Add ability to run Jetty from Gradle.

- Removed ${minifySuffix} from files.
- Added jetty Gradle plugin.
- Removed minifying from build.gradle.
Added build and classes to gitignore.
Gradle task jettyRun starts with System property xmlDataFile=Data.xml,
Merge pull request #3 from jlagerweij/master

Add ability to run Jetty from Gradle