Display python version & platform at repl startup
Display python version & platform at repl startup

*hy/cmdline.py: At the repl startup the Python implementation & version
 is displayed along with the platform(os) information

kartikm/hy,gilch/hy,larme/hy,tuturto/hy,Foxboron/hy,ALSchwalm/hy,aisk/hy,tianon/hy,timmartin/hy,michel-slm/hy,jakirkham/hy,adamfeuer/hy,farhaven/hy,Foxboron/hy,farhaven/hy,larme/hy,aisk/hy,Tritlo/hy,farhaven/hy,larme/hy,algernon/hy,mtmiller/hy,kirbyfan64/hy,zackmdavis/hy,aisk/hy,freezas/hy,kirbyfan64/hy,tianon/hy,paultag/hy,tianon/hy