Create function to allow a new definitions file to be added

[ChrisMarsh82]

Function so that a new definitions file can be added for a station.

inputs: country, station_id, definitions

This should not delete the existing definitions file but date stamp the files added.

Only the latest definitions file should be accessed by the functions. The historical definitions will not need to be accessed at the moment as this work is out of scope of this issue.

[lilyclements]

@ChrisMarsh82 This function belongs in epicsadata since it relates to the data. I have made this function under add_definitions_to_bucket.
I have also amended the function to get the data from the bucket (get_definitions_data). This now will get the most recent definitions data if there is multiple, or otherwise will just get one.

The PR for this in the epicsadata package is given here IDEMSInternational/epicsadata#11

I've then written a wrapper function for epicsawrap so that this can be accessed from this package - this is in PR #57. If you're happy with this, then this issue can be closed as completed

[ChrisMarsh82]

see #90