Updated test_key_pair to use boto

Updated test_key_pair to use boto instead of mrjob since boto is
included with Anaconda by default
Set default vault dir if EC2_VAULT env var isn't defined
Removed password from Creds.pkl

Removed the password from Creds.pkl since it didn’t look like it was
being used and the variable wasn’t defined.
Use Creds.pkl instead of AWSCredentials.py
Make the security group option optional
Updated security group configs

If a security group is defined in ~/Vault/Creds.pkl then the EC2
instance will be launched with that security group. If one isn’t
defined then a security group will be created based on the current ip
address.