Fix bug on CLI for full name image of postgres

[nunojusto]

Problem

Issue https://github.com/CityOfZion/neo-local/issues/97

Solution

After some tries i've made it putting full image name on the postgres image

Checklist

• [x] I have ran the tests locally.
• [x] I branched off of the develop branch and not master.
• [x] I did not change the VERSION file.

[nunojusto]

Sorry I'm PRing from my develop. Next time I will make a feature branch for each PR