Cleanup libuv adapter
Cleanup libuv adapter

This:
  - Removes misplaced libuv function prototype
  - Includes stdlib for free()

Closes #251

hidebug/hiredis,galdor/hiredis,olgeni/hiredis,tattsun/hiredis,arinal/hiredis,rangan337/hiredis,redis/hiredis,owent-contrib/hiredis,tattsun/hiredis,charsyam/hiredis,chenlicong0821/hiredis,nokiddin/hiredis,liulingfree/hiredis,h1048576/hiredis,rangan337/hiredis,Yhgenomics/hiredis,chenlicong0821/hiredis,redis/hiredis,jinguoli/hiredis,thomaslee/hiredis,hidebug/hiredis,thomaslee/hiredis,badboy/hiredis-win,liulingfree/hiredis,xjzhou/hiredis,owent-contrib/hiredis,yiliaofan/hiredis,olgeni/hiredis,galdor/hiredis,jqk6/hiredis,Yhgenomics/hiredis,charsyam/hiredis,jinguoli/hiredis,jinguoli/hiredis,redis/hiredis,xjzhou/hiredis,picrin/redisSamples