Fix since command

 - CLI arg name was incorrect
 - Handle the cases where the database is empty or no tweet is found
Add oauth2 requirement to setup.py
Catch correct exception when getting ID of latest tweet from empty DB
Switch from config_dir to data_dir in archive.py
Retrieve consumer key from config by the correct name
Make the log dir if it doesn't exist
Make imports conditional in CLI script (for faster startup)
Spawn server from the CLI app
Formatting fixes