E2e test send on testnet

[slaweet]

There should be some e2e tests that run with testnet:

• send with testnet
• vote with testnet
• send with Custom Node https://testnet.lisk.io
• vote with Custom node https://testnet.lisk.io

There should be a way to specify a testnet passphrase as an argument of e2e test command, e.g.:
npm run --silent e2e-test -- --params.testenetPassphrase 'wagon stock borrow episode laundry kitten salute link globe zero feed marble' so that we don't need to have the passphrase in the public source code. In Jenkins we can have the passphrase in an environment variable.

The default of the testenetPassphrase param should be something like null, defined here:
https://github.com/LiskHQ/lisk-nano/blob/d69cc1c2f6baf918c9eaea13bb0f41e6c3b8325c/protractor.conf.js#L23-L27

If the testenetPassphrase param is null, then the step can be marked as pending, using: callback(null, 'pending'); [0], so that it is possible to successfully run the e2e tests without a testnet account.

[0] cucumber/cucumber-js#873 (comment)