Layer 7 encryption for node-sdk

[aseveryn-epam]

No description provided.

[coveralls]

Coverage remained the same at 100.0% when pulling addd477 on akreisman-epam:layer-7-node-sdk into 50814fd on hyperwallet:master.

[peter-joseph]

NodeJS version 0.12 and IOJS will fail due to functions does not exist

/home/travis/build/hyperwallet/node-sdk/node_modules/node-jose/lib/algorithms/aes-cbc-hmac-sha2.js:302
var EncryptionLabel = Buffer.from("Encryption", "utf8");
^
TypeError: Buffer.from is not a function
at Object. (/home/travis/build/hyperwallet/node-sdk/node_modules/node-jose/lib/algorithms/aes-cbc-hmac-sha2.js:302:30)
at Module._compile (module.js:430:26)
at Module._extensions..js (module.js:448:10)
at Object.require.extensions.(anonymous function) [as .js] (/home/travis/build/hyperwallet/node-sdk/node_modules/babel-register/lib/node.js:152:7)

Added new library "node-jose": "^1.0.0" causing this to fail
should we adjust our SDK NodeJS versions and deprecate IOJS (since iojs is merged to nodejs)? @bolynykhw
or Polyfill Buffer.from @aseveryn-epam ?
https://nodejs.org/en/docs/guides/buffer-constructor-deprecation

[peter-joseph]

@aseveryn-epam
we will be bumping our NodeJS version support targeting for node-sdk 0.2.0 release, need your help on updating .travis.yml file from your NodeJS PR#7
to

- '4.9.1'     #argon
- '6.15.1'   #boron
- '8.14.0'   #carbon
- '10.14.2' #dubnium
- stable```

removing support on NodeJS `0.12` and `iojs` moving forward our sdk will run on NodeJS LTS versions and latest stable version respectively
basically the versions above are chosen for long term release support (LTS) 
https://nodejs.org/en/download/releases

[peter-joseph]

Please have a look on latest comment, instead of polyfills we will just change NodeJS version support

[peter-joseph]

Thanks @aseveryn-epam looks like coverage is 93% can we bump that back to 100% please
https://coveralls.io/builds/20613086