Tests fail for mathoid-mathjax-node@0.6.0
```
15:42:57 > librsvg@0.6.1 install /home/jenkins/workspace/npm-node-4.3/node_modules/mathoid-mathjax-node/node_modules/librsvg
15:42:57 > node-gyp rebuild
15:42:57
15:42:57 (node) child_process: options.customFds option is deprecated. Use options.stdio instead.
15:42:57 Package librsvg-2.0 was not found in the pkg-config search path.
15:42:57 Perhaps you should add the directory containing `librsvg-2.0.pc'
15:42:57 to the PKG_CONFIG_PATH environment variable
15:42:57 No package 'librsvg-2.0' found
15:42:57 Package cairo-png was not found in the pkg-config search path.
15:42:57 Perhaps you should add the directory containing `cairo-png.pc'
15:42:57 to the PKG_CONFIG_PATH environment variable
15:42:57 No package 'cairo-png' found
15:42:57 Package cairo-pdf was not found in the pkg-config search path.
15:42:57 Perhaps you should add the directory containing `cairo-pdf.pc'
15:42:57 to the PKG_CONFIG_PATH environment variable
15:42:57 No package 'cairo-pdf' found
15:42:57 Package cairo-svg was not found in the pkg-config search path.
15:42:57 Perhaps you should add the directory containing `cairo-svg.pc'
15:42:57 to the PKG_CONFIG_PATH environment variable
15:42:57 No package 'cairo-svg' found
15:42:57 gyp: Call to 'pkg-config --libs-only-l librsvg-2.0 cairo-png cairo-pdf cairo-svg' returned exit status 1 while in binding.gyp.
15:42:57 gyp ERR! configure error
15:42:57 gyp ERR! stack Error: `gyp` failed with exit code: 1
15:42:57 gyp ERR! stack at ChildProcess.onCpExit (/usr/share/node-gyp/lib/configure.js:344:16)
15:42:57 gyp ERR! stack at emitTwo (events.js:87:13)
15:42:57 gyp ERR! stack at ChildProcess.emit (events.js:172:7)
15:42:57 gyp ERR! stack at Process.ChildProcess._handle.onexit (internal/child_process.js:200:12)
15:42:57 gyp ERR! System Linux 3.16.0-4-amd64
15:42:57 gyp ERR! command "/usr/bin/nodejs" "/usr/bin/node-gyp" "rebuild"
15:42:57 gyp ERR! cwd /home/jenkins/workspace/npm-node-4.3/node_modules/mathoid-mathjax-node/node_modules/librsvg
15:42:57 gyp ERR! node -v v4.3.0
15:42:57 gyp ERR! node-gyp -v v0.12.2
15:42:57 gyp ERR! not ok
15:42:57 npm WARN This failure might be due to the use of legacy binary "node"
15:42:57 npm WARN For further explanations, please read
15:42:57 /usr/share/doc/nodejs/README.Debian
```