webp图片格式配置，bundle时web_ffi未成功 22/03/2015
首先安装依赖包
1. 安装依赖包
CentOS:
sudo yum install libjpeg-devel libpng-devel libtiff-devel
Ubuntu:
sudo apt-get install libjpeg-dev libpng-dev libtiff-dev
MaxOS:
sudo port install jpeg libpng tiff
2. Building:
git clone https://chromium.googlesource.com/webm/libwebp cd libwebp ./autogen.sh ./configure make sudo make install
3. 安装webp gem
gem install webp-ffi
4. 如果以上两步装完后，启动服务器并且访问出错，错误信息类似：
.rvm/gems/ruby-2.0.0-p247@tuan800/gems/webp-ffi-0.1.7/ext/webp_ffi/x86_64-linux/libwebp_ffi.so
解决方法：
sudo sh -c ‘echo “/usr/local/lib” > /etc/ld.so.conf.d/user_local.conf’
sudo ldconfig