This change adds features to the heap dump for the cf buildpack to be able to store heap dumps for customers in the object store. It includes the following features:

• Added -XX:+HeapDumpOverwrite flag. This allows a heap dump to overwrite an existing file. It is also need to write to a named pipe. The latter will be used by the buildpack to stream from the named pipe to the object store. You could already do this in the jcmd GC.heap_dump command.
• Added -XX:HeapDumpParallelism=<nr-of-threads> flag. This allows to specify the number of threads to use when writing the heap dump. You could already do this in the jcmd GC.heap_dump command.
• When using only one thread to dump the heap, the code will use additional files apart from the heap dump file. This ensures that no extra disk space is used when using only one thread.
• Added -XX:+LimitPrimitiveArrayContentInHeapDump flag. If enabled, the heap dump will only write the real content for the first elements of large primitive arrays. The rest is filled with 0 (or false for boolean arrays). This makes the heap dump much more compressible, making upload to the object store faster. The number of entries to keep can be set via -XX:StringLikeContentSizeLimitInHeapDump=<limit> for byte and char arrays (default is 120) or -XX:ArrayContentSizeLimitInHeapDump=<limit> for the other primitive arrays (default is 50).

fixes #2250