add simple memcached server. LRU is not implemented.
add memcached footprint test
replace string with StringPiece to save memory.
add PerformanceInspector
fix include path for old version of gperftools.
build C++11 targets
shrink after writing
shrink buffer in a better way.
add memcached-bench
shard mutex
replace snprintf with LogStream.
Fix build for clang 3.3

Contributed by Benyu Zhang <byzhang@gmail.com>
fix warnings for clang.
update clang.diff
Add superfluous check for Mutex and Condition.

Fixed issue 17.
check return value for pthreads
add rvalue overload for C++11
only evaluate argument once in MCHECK macro.
add check for MCHECK().
fix branch expectation