Merge pull request #6 from chen3feng/develop

File and Path
Merge pull request #7 from chen3feng/develop

Add static_class.h, cpplint path
Merge pull request #8 from chen3feng/develop

Add Path::Join
Merge pull request #9 from chen3feng/develop

Add SpinLock, RwLock, Semaphore, ThreadGroup
Merge pull request #10 from chen3feng/develop

Add closure.h.pump and adjust format
Merge pull request #11 from chen3feng/develop

Develop
Merge pull request #12 from chen3feng/develop

Optimze File
Merge pull request #13 from chen3feng/develop

Develop
Merge pull request #14 from chen3feng/develop

Develop
Merge pull request #15 from chen3feng/develop

Fix Issue 4, ...
Merge pull request #16 from chen3feng/develop

Add StringConcat and Http
add thread pool
Merge pull request #21 from chen3feng/develop

Refine http
enhance thread pool
remove the dirty codes in thread pool
remove dirty comment in thread_pool.h
Merge pull request #22 from chen3feng/develop

Add File::GetTimes
fix the mutex scope and some typos
add the task mutex in terminate()
Merge pull request #20 from anqin/develop-threadpool

add thread pool