Visual Studio 2013 compatibility fixes

stresstest/stresstest.cpp
stresstest/util.cpp
stresstest/util.hpp

Compatibility fixes to deal with stricter C++11 interpretations in
Visual Studio 2013:

- Temporary non-const objects should not be bound as references.
http://connect.microsoft.com/VisualStudio/feedback/details/807118

- Random number generators can't be initialized by passing a reference
to std::random_device.
http://connect.microsoft.com/VisualStudio/feedback/details/875492

- std::uniform_int_distribution accepts only short, int, long,
long long, unsigned short, unsigned int, unsigned long and
unsigned long long.
http://connect.microsoft.com/VisualStudio/feedback/details/793763
[stresstest] Advise use of a ramdisk for testing

stresstest/stresstest.cpp

- (main)
Move the csv filename and ramdisk size variable assignments from
generate_and_compare() to here.

Show a warning with the csv filename output path and advising use of a
ramdisk.