Merge 2.4 into master.

Original pull requests:
        #943 from jet47:cuda-5.5-support
        #944 from jet47:cmake-2.8.11-cuda-fix
        #912 from SpecLad:contributing
        #934 from SpecLad:parallel-for
        #931 from jet47:gpu-test-fixes
        #932 from bitwangyaoyao:2.4_fixBFM
        #918 from bitwangyaoyao:2.4_samples
        #924 from pengx17:2.4_arithm_fix
        #925 from pengx17:2.4_canny_tmp_fix
        #927 from bitwangyaoyao:2.4_perf
        #930 from pengx17:2.4_haar_ext
        #928 from apavlenko:bugfix_3027
        #920 from asmorkalov:android_move
        #910 from pengx17:2.4_oclgfft
        #913 from janm399:2.4
        #916 from bitwangyaoyao:2.4_fixPyrLK
        #919 from abidrahmank:2.4
        #923 from pengx17:2.4_macfix