Run command doesn't take environment into account when building

[leonderijke]

The bin/maji run always builds with the production environment, no matter if I specify a different env via --env or the NODE_ENV environment variable.

I'm pretty sure that is because cordova-exec calls bin/maji build to build the assets, but without passing through the env.

I worked around this by changing the bin/maji build command to read the process.env.NODE_ENV as well.