title: Package cairo was not found in the pkg-config search path. Node j.s install canvas issue
body: <p>I am having a problem installing installing the canvas module in node..It seems to be something with cairo I am getting this error...</p>
  
  <pre><code>npm http GET https://registry.npmjs.org/canvas
  npm http 304 https://registry.npmjs.org/canvas
  npm http GET https://registry.npmjs.org/nan
  npm http 304 https://registry.npmjs.org/nan
  
  &gt; canvas@1.1.3 install /Users/plimb/Desktop/motion-therapy/node_modules/canvas
  &gt; node-gyp rebuild
  
  Package cairo was not found in the pkg-config search path.
  Perhaps you should add the directory containing `cairo.pc'
  to the PKG_CONFIG_PATH environment variable
  No package 'cairo' found
  gyp: Call to './util/has_cairo_freetype.sh' returned exit status 0. while trying to load binding.gyp
  gyp ERR! configure error
  gyp ERR! stack Error: `gyp` failed with exit code: 1
  gyp ERR! stack     at ChildProcess.onCpExit (/usr/local/lib/node_modules/npm/node_modules/node-gyp/lib/configure.js:424:16)
  gyp ERR! stack     at ChildProcess.EventEmitter.emit (events.js:98:17)
  gyp ERR! stack     at Process.ChildProcess._handle.onexit (child_process.js:789:12)
  gyp ERR! System Darwin 13.0.0
  gyp ERR! command "node" "/usr/local/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "rebuild"
  gyp ERR! cwd /Users/plimb/Desktop/motion-therapy/node_modules/canvas
  gyp ERR! node -v v0.10.21
  gyp ERR! node-gyp -v v0.10.10
  gyp ERR! not ok
  npm ERR! weird error 1 
  npm ERR! not ok code 0
  </code></pre>
  
  <p>I'm not sure what it all means! Would appreciate any help!For example how to a mkdir cairo pc in the pkg_config_path environment variable? </p>