Update canvas dependency version

[ruKurz]

node-sprite-generator version 0.10.2 depends on canvas 1.3.12. https://github.com/selaux/node-sprite-generator/blob/0.10.2/package.json#L15

Since canvas 1.3.12 has some issues that have been solved with version 1.6.3:

• Clang build error wrt isnan and isinf #863
• Failed at the [email protected] install script 'node-gyp rebuild'

it would be great to see a new release of node-sprite-generator with an updated canvas version. In the master branch the canvas dependency is already updated: https://github.com/selaux/node-sprite-generator/blob/master/package.json#L16

[ruKurz]

https://www.npmjs.com/package/@zouloux/node-sprite-generator does not need canvas at all.