[WIP] Update eslint & remove JSCS

[gucong3000]

Blocked: gulpjs/eslint-config-gulp#13

[demurgos]

I'll repeat my comment from #11:

plugin-error is part of gulp: it still has to support Node 0.10.

Regarding the other changes, I'll let @phated comment. He did a recent commit to normalize the repo to match the other Gulp repos.

[phated]

As @demurgos said - this isn't being updated until we start working on the gulp 5 stuff which isn't even on the roadmap yet.

[gucong3000]

I updated my commit to keep support Node 0.10.

.travis.yml:

sudo: false
language: node_js
node_js:
  - 'stable'
  - '8'
  - '6'
  - '4'
  - '0.12'
  - '0.10'
script:
  - if [ "$TRAVIS_NODE_VERSION" = "stable" ]; then npm test; else npm run coveralls; fi