Fix ISH-lite reader

[bbakernoaa]

This fixes multiple issues in the ish_lite reader #104 .

• Adds verbose flag to print out step by step changes for debugging purposes
• fix the history reader to get the dates available correctly
• build_url now ensures that it only reads data available by directly looking at each year url to gather all the individual site urls
• slims the data to only the target dates
• merges the meta data from history back into the frame