Merge pull request #41 from datacratic/tracing-fixes

Fixes for RTBKit tracing system
EndpointBase now exposes a load factor metric.
load monitoring in the enpoint now includes both branches.
Merge pull request #42 from datacratic/tracing-fixes

Fixes for gcc 4.6
made map value description more general with helper functions for key stringify/unstringify
link libservices.so against liboost_system
epoller: tolerate errors when removing fds that were already closed
enabled templating of stringToKey and keyToString conversion functions
fixed and tested templatization of ValueDescription<std::map<K,V>>
Fixed linking errors with old versions of boost.
Fixed the namespace of the tracing mechanism.
Runner: exit from the wrapper process using _exit, to void executing functions registered from the parent via atexit
Fixed static field initialization