Update babel-preset-es2015 to babel-preset-env

[RamYadlapalli]

We are using react-select in our projects. Recently we updated babel-preset-es2015 to babel-preset-env to keep upto date but we still need to maintain es2015 preset in our devDependencies because of react-select devDependencies.

So please update the babel-preset-2015 to babel-reset-env.
Some notes on Babel-preset-env: Without any configuration options, babel-preset-env behaves exactly the same as babel-preset-latest (or babel-preset-es2015, babel-preset-es2016, and babel-preset-es2017 together). And it is highly recommended to use this preset