Remove the support for python3 from installation.md (#15)

* delete the support for PY3

Author: lilong12

docs/installation.md

@@ -5,10 +5,12 @@
 版本要求：
 
 * PaddlePaddle >= 1.6.2
-* Python 2.7 or 3.5+
+* Python 2.7+ (python2 only)
 
 关于PaddlePaddle对操作系统、CUDA、cuDNN等软件版本的兼容信息，请查看[PaddlePaddle安装说明](https://www.paddlepaddle.org.cn/documentation/docs/zh/beginners_guide/install/index_cn.html)
 
+备注：当前版本尚不完全兼容PY3。
+
 ### pip安装
 
 当前，需要在GPU版本的PaddlePaddle下使用大规模分类库。

setup.py

@@ -46,10 +46,6 @@
         'Intended Audience :: Science/Research',
         'License :: OSI Approved :: Apache Software License',
         'Programming Language :: Python :: 2.7',
-        'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.4',
-        'Programming Language :: Python :: 3.5',
-        'Programming Language :: Python :: 3.6',
         'Topic :: Scientific/Engineering',
         'Topic :: Scientific/Engineering :: Mathematics',
         'Topic :: Scientific/Engineering :: Artificial Intelligence',