+ added consistent hash map
 * update travis to download gmock
Merge branch 'master' into add_ch_ring
 * Temporarily reduce the compiler warning level
* partitally modified ch according to code review.
Merge branch 'add_ch_ring' of github.com:vsfs/vobla into add_ch_ring
* more modification
* modification according to code review.
* resloved conflicts in Makefile.am & configure.ac

Conflicts:
	configure.ac
	vobla/Makefile.am
+ added boost library to travis build server
* Modification according to code review
* corrected gmock URL in travis.xml and README.
* commented out	the unused CXXFLAGS in configure.ac.
* removed explicit keyword for ConsistentHashMap constructor.
* corrected back the google mock URL
 * Added back the compiler warning -Werror and bypass the warnings for gmock
Merge branch 'master' of github.com:vsfs/vobla into add_ch_ring

Conflicts:
	.travis.yml
* third modifcation according to code review
* updated comments.
* added definition of operator[].
* unified All Key to key_type.
* deleted the const keyword for key_type.
* fixed the g++ 4.7 cmd error.travis.yml
* comment out operator [] in ch ring
Merge pull request #4 from vsfs/add_ch_ring

Add Consistent Hash Ring lib