Updated MemoryManager to not to wait for Cleaner to finish when low on memory. Now Memorymanager itself will halt new allocations immediately after gc run, if memory usage is too high.
Added a flag in a call to MemoryManager which should enable to attempt allocation without blocking, which is to be used in cases when you need to allocate memory to free memory not hold in K/V store (e.g. NewChunk.compress)
Merge branch 'master' of github.com:0xdata/h2o