Improving folder structure so that example folder would be visible to maven

This pr contains 2 main changes:
1- Get rid of ant build: I think it's not necessary to keep supporting 2 build tools. Having the maven pom is enough since there is no binding with ant scripts.
2- Change folder structure to meet maven conventions: I moved the parser source under jparsec, moved the examples under jparsec-examples and added a test utils project used by both jparsec and jparsec-examples.