* chore: use openapi-core to bundle definition instead of json-schema-ref-parser
* chore: update: root and demo webpack configs
* chore: refactor loadAndBundleSpec
* chore: update vesions: openapi-core, redoc
* chore: rolled back webpack.config(s) to previous version
* chore: changed the way of creating core Config for bundling definition
* fix: disable eslint react/display-name
* fix: update nodejs version to 12 in travis config
* chore: optimize verification: browser or server
* chore: add fetch only for browser
* Update src/utils/loadAndBundleSpec.ts
* chore: isBrowser verification improvment
Co-authored-by: Roman Hotsiy <gotsijroman@gmail.com>
