v0.3

Third prototype.

• Compiles and runs.
• Added a command-line argument for fetching by different authorID (example: ./go_parser 9).
• Additional page requests (beyond the first page) are fetched concurrently
• Book titles are reconstructed from the http requests, maintaining pagination order, into a map[int]string

Instructions:

go build . (from repo directory)
./go_parser (retrieves author ID from 'books.xml' file)
./go_parser 9 (author ID set to 9)

Other ID's to try: 9, 16, 18, 26, 49, 58, 68, 119, 159, 229, 236, 282, 387, 399