在RTF中引入httplibrary

　　本来运行pip install --upgrade robotframework-httplibrary即可直接将httplibrary包安装好后，但因为网络问题，pip找不到robotframework-httplibrary，只好在https://github.com/peritus/robotframework-httplibrary下载了robotframework-httplibrary-0.4.2手动安装，之后运行例子时，出现如下报错：

1. Importing test library 'HttpLibrary.HTTP' failed:ImportError: No module named webtest, 于是在https://nodeload.github.com/Pylons/webtest/tar.gz/master下下载了webtest进行python setup.py install

2.  再报 Importing test library 'HttpLibrary.HTTP' failed:ImportError: No module named jsonpointer，运行easy_isntall jsonpointer提示安装成功。

３.再报 Importing test library 'HttpLibrary.HTTP' failed:ImportError: No module named jsonpatch，运行easy_isntall jsonpatch，终于pass啦

　　　httplibrary的api在如下链接中可以查到：http://peritus.github.io/robotframework-httplibrary/HttpLibrary.html