fix file: xinteger.h
Merge pull request #13 from guangbin79/fix_integer

fix file: xinteger.h, merge.
api impl demo - 1
实现xrand，xtapi的.c文件
Merge pull request #15 from guangbin79/feature_http

api impl demo - 1
fix file: xhttp.h/xthread.h/xtimer.h
Merge pull request #19 from guangbin79/fix_system_api

fix file: xhttp.h/xthread.h/xtimer.h
Merge branch 'master' of github.com:tiros-com-cn/xC