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
Would you change it to ```{0}``` as the empty braces format was introduces only in [Python >2.7](https://docs.python.org/2/library/string.html#format-examples). IMHO, we shouldn't introduce language version restriction if it is not necessary.