revamped models to simplify
added fields to keep track of data update
updated initialize.py
modified settings.py and removed settings2
use DateTimeField in models so that datetime object can be use in query
upgraded get_all_symbols to get_symbols_to_update_data
added routine to update historical prices
fixed a bug in piping
initialize module will do initialization for other working scripts
new create_tables module to create tables
added logging settings