Use GNUInstallDirs variables for install destination

Since we depend on CMake 2.8.7 we can do it (it's included in CMake
since 2.8.5)

The main effect is that on Debian/Ubuntu, libraries will be installed
in lib/${arch}/ instead of in lib, enabling installation for
multi-architecture (see http://wiki.debian.org/Multiarch)

Also it makes no longer necessary to remember to use lib${LIB_SUFFIX}
to install in the correct lib dir since it is handled automatically.
Merge pull request #89 from drdanz/GNUInstallDirs

Use GNUInstallDirs variables for install destination
Fixing yarp-config compilation on Windows and string-related inconsistencies
Removing spurious line from commit 070c2a6eb688547b3bdc4dd2c6feb78c5f34be2a
Link pthread as private

This fixes the CMP0023 warning with cmake 2.8.12
Disabled warnings when compiling 'diff' library on Windows
[ResourceFinder] Use native path separators when providing paths
[Cleanup] Clean testing scripts

Use CTest instead of Darts
Moving YARP_COMPILE_TESTS option to YarpOptions.cmake. Fixes #92
[yarpros] yarp::os::BufferedPort knows the type of its content, so why not pass it on
fix enforcement of input-only ports for pull carriers
substr in C++ needs initial position to be in range
simplify json request syntax so that ?req=... in url implies json format
Change status type from int to nite::SkeletonState in all getSkeletonState(int) methods
Quit OpenNI2DeviceServer if sensor cannot be found or cannot be initialized
Remove bool argument from updateInterface() (obsolete concept from OpenNIv1.x)
Remove getSkeletonState() method
Add parameter for minimum confidence
Add information for the verbose parameter
Add ONI playback and record functionality