uploadr: change methods to functions

The grabNewImages and reportError methods have been moved to functions
since they don't rely on anything in the class instance.
uploadr: let the logging API format the string
uploadr: do not overwrite flickr module name

Using 'import flickr' creates a module in the outer scope called flickr,
but reusing this as a variable name here caused confusion.
uploadr: put the allowed extensions in a constant

Fix the overly long line by moving the extensions used out to a constant.