Make Query Generators Into Dynamic Modlues

Move bingQueriesGenerator to queryGenerators folder
main.py add queryGenerators folder to PATH
Add <queries> tag to config file
Modify config.py to read <queries> tag
Make bingQueriesGenerator dynamic loadable
I think I won't have time to test it well enough. The code looks good. Do you prefer to finish the wikisearch and then have one big pull request or rather go with that one and have a new request later?