Examples broken with last nodeJS canvas versions

[adadgio]

I'm just trying the examples here and noticed too problems:

1. node canvas is not listed as a dependency in the project, i am not sure it should be but it seemed to me that it should (seeing the examples and how the library works).

2. With latest canvas version (ex. 2.2.0 and above), new Canvas(...blah) is not a constructor and should be used this way: const canvas = Canvas.createCanvas(...blah). Maybe the examples should be updated.

Cheers !