* Implements ability to defer seed phrase backup to later
* Adds incremental-security.spec.js, including test dapp that sends signed tx with stand alone localhost provider
* Update metamask-responsive-ui for incremental account security changes
* Update backup-notification style and fix responsiveness of seed phrase screen
* Remove uneeded files from send-eth-with-private-key-test/
* Apply linguist flags in .gitattributes for send-eth-with-private-key-test/ethereumjs-tx.js
* Improve docs in controllers/onboarding.js
* Clean up metamask-extension/test/e2e/send-eth-with-private-key-test/index.html
* Remove unnecessary newlines in a couple first-time-flow/ files
* Fix import of backup-notification in home.component
* Fix git attrs file
* eslint: Check for unused function arguments
* eslint: Ignore unused '_' in argument list
Also allow any number of '_' e.g., '__' or '___' which is to be used sparingly
* Remove and rename unused arguments
