Merge in CASA/casa6 from CAS-14382 to master
* commit '5f09eac5811a1590a5825e41fa189531b8973a40':
Fixed check for existing file
fixed path to data issues and updated connection failure message
moved igs_file parameter creation outside of the try statment... Still looking at why the mac build is failing on the branch
Put the whole attempt to grab data in the try
first attempt at switching to using ftplib for getting tec data