Typo fix in image.test.js
Added SVG image loading functionality

There are 3 new methods added in Image.cc:
  * isSVG - Attempts to identify if buffer data contains an SVG
image. It checks if the initial bytes start either with 'svg'
or 'xml'. Lower case letters only!
  * loadSVGFromBuffer - Load SVG image from buffer and renders to
Cairo surface.
  * loadSVG - Load a complete SVG file and then calls loadSVGFromBuffer.
This is pretty much the same as loadGIF.
Added SVG tests and fixtures
Added server side tests and fixtures
Added svg to png convert test

This test loads an SVG buffered file data into an Image and then
draws the buffered data onto a Canvas context. After that it
converts the Canvas data to PNG data.