Upgrade dependencies

[ota-meshi]

I upgraded some dependent packages.

Also, I added some tests to TravisCI's configuration file to check if it works with the old packages.

[tpraxl]

Found this PR because of an own project dependency to eslint-plugin-vue that depends on vue-eslint-parser and makes yarn check fail with:

error "eslint-plugin-vue#eslint@^5.0.0" doesn't satisfy found match of "eslint@6.2.2"
error "vue-eslint-parser#eslint@^5.0.0" doesn't satisfy found match of "eslint@6.2.2"
error "eslint-plugin-vue#vue-eslint-parser#eslint@^5.0.0" doesn't satisfy found match of "eslint@6.2.2"

Please consider making vue-eslint-parser compatible to eslint 6

[tpraxl]

Please merge this PR.

[sodatea]

Ping @mysticatea

[rchl]

eslint-plugin-vue has now upgraded to support eslint 6 and is using this dependency so we get peer dependency warnings because of that.

[mysticatea]

Thank you for your contribution and I apologize for the lack of my activity.