Issue originally made by @aoberoi

Bug information

• Babel version: 6.2.0
• Node version: 4.2.2
• npm version: 2.14.7

Description

I'd like to be able to declare my "extensions" inside my .babelrc file so that anyone running babel-cli in the project directory will get the same "extensions" option I chose. As I understand, this would mean extending the general options for babel to use extensions, rather than baking that into the babel-cli module. I think this makes sense because the extensions in which the code is authored is more a concern at the project level than a concern that someone could have regarding where input comes from and where output goes to (such as the current babel-cli options).