Add class to <canvas>

[noamyg]

Hi, In this example of drawing over image, the <canvas> tag gets a custom class. Is it possible to add it to the nested <canvas> of <signature-pad>?

Thank you

[wulfsolter]

Between https://github.com/wulfsolter/angular2-signaturepad/blob/417bba565de80033bfd95504699c53dd92719490/signature-pad.ts#L15-L18 and https://github.com/wulfsolter/angular2-signaturepad/blob/417bba565de80033bfd95504699c53dd92719490/signature-pad.ts#L37-L52

it looks like it would be quite straightforward. However given that I don't use this repo anymore I'm more inclined to review/merge a PR :)

[Srinivasan95-RB]

Hi, is this done? This will be a very useful feature indeed.