Don't use insight on CI builds

bem-tools 1.0.0 on travis always fails because of insight permissions request. [Example](https://travis-ci.org/bem/bem-core/jobs/10972998).
The solution is to check `CI` enviroment variable to determine if we are running in continious integration enviroment.  Approach with checking `process.stdin.isTTY` didn't work - it's always `true` on travis.

We need to publish new release when this will be merged. This issue is blocking bem/bem-core#239 and bem/bem-components#188.

/cc @scf2k @arikon