Add ProfilePicture to User

[Refs #72499862]
Generated ProfilePicture uploader, generated required migrations,
migrated the db.
Update .gitignore

[Refs #72499862]

Added /public/uploads folder to .gitignore
Update UsersController, 'welcome' layout

[Refs #72499862]

Added file_field to the layout, made profile_picture a permitted param.
Add Country model

[Refs #72499862]

Generated Country model, established association between Users and
Countries, added country select on the ‘welcome’ page.
Add Link model

Created new model, that keeps user’s links to social sites
Update UsersController

[Refs #72499862]

Updated UsersController to accept links,
updated User model (has_one :link)
Update Gemfile

Updated rspec to 3.0.1
Generate rspec helpers

[Refs #72499862]
Update user.rb