cmake: Use -std=c++0x instead of -std=gnu++0x

Old flags didn't work with clang. Now both gcc and clang work fine.
cmake: Reorganize build options

This commit makes usage from CMake 'option()' keyword for boolean build options
to make it straightforward and to work better with IDEs (KDevelop in its
interface can change them using checkboxes).
String options have also their values printed to be sure that build's
configured properly.
tests: Add README file

This file contains information about launching and creating functional tests.