Check Signature and Force dates, and add End dates

[jaeltan]

Check Signature and Force dates, and add End dates where they can be found.

[jaeltan]

Revert HUGGO dataset to original (before changes were made) and save as .csv file in data-raw/agreements/HUGGO folder. Rows with changes made by @AndersIHEID should be kept separately in a new .csv file in the data-raw/agreements/HUGGO folder. Add a line in the preparation script to merge the two .csv files at the end when coding is completed.