Update packages eslintignore to point to configuration in root

[Matt-Butler]

When running npm run lint in an individual package, the .eslitignore file is not honored.

Update

    "lint:js": "../../node_modules/.bin/eslint **/*.js, **/*.jsx",

to

    "lint:js": "../../node_modules/.bin/eslint **/*.js, **/*.jsx --ignore-path ../../.eslintignore",

[Matt-Butler]

http://eslint.org/docs/user-guide/configuring#using-an-alternate-file

[bjankord]

@Matt-Butler and I tested this some more.

We landed on updating
"lint:js": "../../node_modules/.bin/eslint **/*.js, **/*.jsx",
to
"lint:js": "$(cd ..; npm bin)/eslint --ext .js,.jsx . --ignore-path ../../.eslintignore"

For the component package.json files

For the root package.json, we can update it to the following:
"lint": "eslint --ext .js,.jsx .",