Add tests for valid and invalid integer literals (closes #373)
Add tests for valid and invalid integer literals (closes #373)

Some of these tests currently fail because of:
https://issues.apache.org/jira/browse/GROOVY-7385

traneHead/groovy-core,shils/incubator-groovy,paulk-asert/incubator-groovy,avafanasiev/groovy,avafanasiev/groovy,dpolivaev/groovy,jwagenleitner/incubator-groovy,shils/groovy,avafanasiev/groovy,armsargis/groovy,avafanasiev/groovy,fpavageau/groovy,jwagenleitner/groovy,traneHead/groovy-core,armsargis/groovy,apache/incubator-groovy,jwagenleitner/incubator-groovy,russel/groovy,paulk-asert/incubator-groovy,paulk-asert/groovy,jwagenleitner/incubator-groovy,apache/incubator-groovy,bsideup/incubator-groovy,graemerocher/incubator-groovy,paulk-asert/incubator-groovy,apache/groovy,paulk-asert/groovy,dpolivaev/groovy,shils/incubator-groovy,apache/incubator-groovy,shils/groovy,jwagenleitner/incubator-groovy,bsideup/incubator-groovy,shils/incubator-groovy,dpolivaev/groovy,shils/groovy,apache/groovy,alien11689/incubator-groovy,apache/groovy,traneHead/groovy-core,dpolivaev/groovy,paulk-asert/incubator-groovy,paulk-asert/incubator-groovy,jwagenleitner/groovy,russel/groovy,fpavageau/groovy,russel/groovy,paulk-asert/groovy,traneHead/groovy-core,russel/incubator-groovy,apache/incubator-groovy,russel/groovy,russel/incubator-groovy,graemerocher/incubator-groovy,graemerocher/incubator-groovy,fpavageau/groovy,bsideup/incubator-groovy,shils/incubator-groovy,armsargis/groovy,paulk-asert/groovy,jwagenleitner/groovy,bsideup/incubator-groovy,alien11689/incubator-groovy,alien11689/incubator-groovy,apache/groovy,jwagenleitner/groovy,russel/incubator-groovy,alien11689/incubator-groovy,armsargis/groovy,fpavageau/groovy,graemerocher/incubator-groovy,russel/incubator-groovy,shils/groovy