Set Application to use postgreSQL.

Signed-off-by: Joseph Gabriel Zafra <joseph.zafra@gmail.com>
Added Strong_parameters to the gemfile.
Added Item Crud.

The item crud manages the items entered in the system.
Each item has a corresponding price that will be used when
the customer bills out.
Removed users model.

This was a test which was accidentally included in the commit.
Removing it to be safe.
Merge pull request #1 from jmalvinchin/item-crud

Item crud