Updated heap size for "run" task

We want to run with a heap big enough, otherwise we just do garbage collection...

build.gradle

@@ -130,6 +130,7 @@ project(':core') {
 
     run {
         systemProperty 'java.library.path', papi_library_path
+ 	applicationDefaultJvmArgs = ['-Xmx6g']
         mainClassName = 'se.lth.cs.Main'
         workingDir = '..'
     }