add support for postgress sql

[prabirshrestha]

No description provided.

[mholt]

Can you please give a detailed description of what you mean? Enough so that someone who is going to work on the issue can sit down, know what you want done, and actually implement it.

[prabirshrestha]

Currently it data is stored in sqlite db. I would like to run this in the cloud so would be good if I could use other db such as postgresql.

[mholt]

(Closing for same reason as described in #30)