Add an integration test for images from mobile
user
```coffeescript
faker  = require 'faker'
fs     = require 'fs-extra'
path   = require 'path'
should = require 'should'

Cozy  = require '../helpers/integration'
Files = require '../helpers/files'


# Images imported from cozy-mobile are special because they have no checksum
describe 'Image from mobile', ->
    @slow 1000
    @timeout 10000

    before Cozy.ensurePreConditions
    before Files.deleteAll
    before Cozy.registerDevice

    file =
        path: ''
        name: faker.commerce.color()
        lastModification: '2015-10-12T01:02:03Z'
    expectedSizes = []

    before 'Create the remote file', (done) ->
        fixturePath = path.join Cozy.fixturesDir, 'chat-mignon-mod.jpg'
        Files.uploadFile file, fixturePath, (err, created) ->
            file.remote = id: created.id
            file.size = fs.statSync(fixturePath).size
            done()

    before 'Remove the checksum', ->
        @app.instanciate()
        client = @app.remote.couch
        client.get file.remote.id, (err, doc) ->
            should.not.exist err
            delete doc.checksum
            client.put doc, (err, updated) ->
                should.not.exist err

    before Cozy.sync
    after Cozy.clean

    it 'waits a bit to do the synchronization', (done) ->
        setTimeout done, 5000

    it 'has the file on local', ->
        files = fs.readdirSync @basePath
        files = (f for f in files when f isnt '.cozy-desktop')
        files.length.should.equal 1
        local = files[0]
        local.should.equal file.name
        size = fs.statSync(path.join @basePath, local).size
        size.should.equal file.size

    it 'has the file on remote', (done) ->
        Files.getAllFiles (err, files) ->
            files.length.should.equal 1
            remote = files[0]
            remote.name.should.equal file.name
            remote.size.should.equal file.size
            done()
```
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