Configurable configuration folder for cta command line tools

Since we are looking to install the cta-cli RPMs on machines like aiadm where we may not be able to have our configuration options in /etc/cta, @jleduc has proposed the following changes to the cta cli tools:

• Have two config folder locations: Tools should look for config files in $HOME/.cta, if it does not exist, then in /etc/cta
• Allow specifying the config file location with a command line flag, disabling the previous behaviour.