Use strict made sense

Fix of errors

`
Connect
500 ReferenceError: user is not defined

    at Object.exports.show [as handle] (/home/beautyfree/roofim/app/controllers/users.js:106:8)
    at next_layer (/home/beautyfree/roofim/node_modules/express/lib/router/route.js:103:13)
    at Object.exports.requiresLogin [as handle] (/home/beautyfree/roofim/app/middleware/authorization.js:9:37)
    at next_layer (/home/beautyfree/roofim/node_modules/express/lib/router/route.js:103:13)
    at Route.dispatch (/home/beautyfree/roofim/node_modules/express/lib/router/route.js:107:5)
    at /home/beautyfree/roofim/node_modules/express/lib/router/index.js:213:24
    at Function.proto.process_params (/home/beautyfree/roofim/node_modules/express/lib/router/index.js:284:12)
    at next (/home/beautyfree/roofim/node_modules/express/lib/router/index.js:207:19)
    at next (/home/beautyfree/roofim/node_modules/express/lib/router/index.js:182:38)
    at next (/home/beautyfree/roofim/node_modules/express/lib/router/index.js:182:38)
`