[fix] issue 7-undefined reference to clock_gettime

platform:
rela@yijie-ThinkPad-L412:~/work/dysonltd-gts$ uname -a
Linux yijie-ThinkPad-L412 3.2.0-55-generic #85-Ubuntu SMP Wed Oct 2 12:29:27 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

compiler:
rela@yijie-ThinkPad-L412:~/work/dysonltd-gts$ gcc --version
gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Merge branch 'develop' into colortrack
[fix] change colortracker to ColorTracker
[add] tracker selection in Runs->Track Robot
[fix] color calibration btn enable/disable
[fix] disable automatic gray if hueGray selected
[fix] RGB order mistake
[add] log traces
[add] getters/setters and method (autocalib)
[fix] work with normalized values
[add] color calib interface
[add] trackers may ask for color images
[fix] return true on colortracker loadtarget
[fix] auto cc method was inverted
[fix] const stuff
[fix] rm compiler warning on unused
[fix] convert l,r distances to pixel units
[fix] cleanup un-unsed stuff
[fix] cleanup widget unused stuff
[fix] whitespace