Use uniform date format in tests

Part of work on #4416.
Reset default date format on login error

When unlogged, the default format is MM/dd/yyyy.

Part of work on #4416.
Get GC custom date on every succesful login

Part of work on #4416.
fix #4416: new preferences page on geocaching.com
Use English when parsing date

Part of fix for #4416.
fix javadoc warning
Merge branch 'issue-4416' into release