Preliminary support for "date added" fields

This isn't yet finished, it needs some input on how to organize the data, and actually where to implement the use of this data, but it already works in setting the date
Using time.time() to store the import time
Formatting the import time in the view and paths

Added the %format{} template function to output the time to any format supported by time.strftime()
Support for date/time fields
correcting identation
Merge pull request #264 from duailibe/master

Adding support for the "Date added field"