fix postgresql:link

use $3 in there, since it actually points to a postgresql instance name
Merge pull request #28 from elia/master

Add db url to the info command
Merge pull request #27 from piranha/patch-1

fix postgresql:link
Added database dump
Added database restore
README.md updated
Check if pg_dump/psql are installed
Fixed two small typos
Removed unecessary 'DB_IMAGE' variables
Refactored PostgreSQL tools check (@Zenedith tip)
Refactored PostgreSQL container check (@Zenedith)
Merge pull request #29 from myhro/master

Two new commands: dump and restore
Fiexd typo on Postgresql tools check function call
Changed 'app' to 'db', as their names may differ
Fixed list command when there are no containers
Merge pull request #31 from myhro/listfix

Fixed list command when there are no containers
Merge pull request #30 from myhro/typofix

Fiexd typo on Postgresql tools check function call
Redirect PortgreSQL tools check output to stderr
Merge pull request #34 from myhro/fix-pgtoolcheck

Redirect PortgreSQL tools check output to stderr
Merge pull request #36 from elia/master

Auto-start pg containers at linked app deploys