Add new command: boliau-readasjson - read a endpoint as a json.

USAGE:

$ boliau-readasjson http://www.news-pac.com/api/topic/蔡英文 limit=1 | boliau-print
fix readasjson bug: logic error if a http url ends with a .json

the program thinks the endpoints is a file which is wrong.
github plugin; init
update requirements.txt
Merge branch 'master' into develop

Conflicts:
	boliau/actionlib.py
	boliau/cmd.py