ULib - This patch adds PostGres test alongside with minor fix

This patch adds PostGres test database alongside with minor fix...

All tests are passing as per [my Travis-CI build log](https://travis-ci.org/stefanocasazza/FrameworkBenchmarks/builds/45049685)
Hi,
the variable indicates how much memory to preallocate to the global memory pool in its various segments of stack, [for details see](https://github.com/stefanocasazza/ULib/blob/master/include/ulib/internal/memory_pool.h)