adds user model; Squashed commit of the following:

commit 0004a52638efb02a4eca03fbbcb07b3882149a99
Author: Josh Justice <josh@need-bee.com>
Date:   Mon Jul 14 07:25:59 2014 -0400

    adds secure password

commit 708000f50dd4df4cdd42ed31ffdfe04128f4e028
Author: Josh Justice <josh@need-bee.com>
Date:   Mon Jul 14 07:14:18 2014 -0400

    adds uniqueness db constraint

commit 4dd87846b2427a21929bf8be60afdb412a4bae5a
Author: Josh Justice <josh@need-bee.com>
Date:   Mon Jul 14 07:11:33 2014 -0400

    email uniqueness validation

commit deea692360042b759d3a0cb8e150d277858bf019
Author: Josh Justice <josh@need-bee.com>
Date:   Mon Jul 14 07:02:31 2014 -0400

    adds more validations

commit 678f86153169c11e9af79d1a189928b25d97c492
Author: Josh Justice <josh@need-bee.com>
Date:   Mon Jul 14 06:56:02 2014 -0400

    validates presence

commit bd5a4004f35d80509769e909a0fec00e722e989d
Author: Josh Justice <josh@need-bee.com>
Date:   Mon Jul 14 06:52:13 2014 -0400

    adds user model