lock free java function execution stats collector

1. Use configuration file to define the monitored functions at startup time
     1. set environment variable SimpleMonitorYaml="the location of the conf"
     2. the configuration file is in Yaml format
         class.name1:
           - function1
           - function2
         class.name2:
           - function1
           - function2
2. Use OSGI WeavingHook to wrap a try/finally block around the monitored function body
3. Collect stats in working thread w/o any lock, save the stats on ThreadLocal map
4. A seperate aggregation thread will consolidate the result and dump to the console


         +--------------+
         |Thread 1      |
         |      +-------+
         |      |stats 1|<----+-
         +------+-------+     |      +--------------------+
                              |      | Aggregation Thread |
         +--------------+     |      |--------------------|
         |Thread 2      |     +------+                    |
         |      +-------+            |  final_stats       |
         |      |stats 2|<-----------+  for stat in 1..n  |
         +------+-------+            |    final_stats     |
                                     |      += stat       |
                +                    |    reset stat      |
                |                    |                    |
                |                    |  log(final_stats)  |
                +                    |                    |
         +--------------+     +------+                    |
         |Thread n      |     |      +--------------------+
         |      +-------+     |
         |      |stats n|<----+
         +------+-------+