Request: Allow setting of Producer

[SenseAndImage]

jsPDF automatically adds Producer and creationdate meta data. The information, that a PDF was created by jsPDF and also adding the version number can be seen as a "Information disclosure vulnerability".

Mitigation:

• either do not expose jsPDF the version at all
• or provide a dedicated function to set the producer data (e.g. putInfo() could be made public and except properties).