watch mode for pspg

I released version 2.5.0 of pspg.

Major feature of this release is possibility to bypass psql and take data from Postgres directly (option: -q, --query). Now the pspg can be used like very simple Postgres client. The main benefit of this feature is in relation to new watch mode. The result of query can be refreshed every n seconds (option: -w). It's allow to use the pspg for simple fresh data presentations, for simple monitoring. The refreshing can be stopped/started by pressing space.