Updated user response due to server side API change

Bug fixed where non existent fields where deleted (fields no longer reported in this version of the Keepa server side response)

Using datetime instead of numpy.datetime64

From testing it appears that matplotlib doesn't like numpy.datetime64 and seems to prefer datetime formatted as a datetime.datetime object.

Initial Release

Initial release contains includes product query API and basic plotting software. Statistics (such as moving mean and 90 day average) will be included in the next version update. Additional queries, such as searching for deals and searches on Amazon, will be included at a later date.