New backend, new query

[janzal]

• Added mongodb (mongoose) store (+test)
• Added Object - Role request

[maksimkurb]

Update package.json:

"dependencies": {
    "eventflow": "0.0.6",
    "async": "~0.1.22",
    "mongoose": "~3.8.1"
}
...

to

"dependencies": {
    "eventflow": "0.0.6",
    "async": "~0.1.22"
},
"optionalDependencies": {
    "mongoose": "~3.8.1"
}
...

optionalDependencies docs