Support for ASIN as an output scheme keyword

[tylernguyen]

Hi,

My preferred directory scheme is:

Author

• Book (Year) [ASIN]
  • Book - Subtitle (Year)

Please add support for ASIN an output scheme keyword. This would also be helpful considering that Audnexus.bundle can quickmatch if there is an ASIN present in the folder name.

[djdembeck]

Added in latest #132