Add grunt exec:createDeb
- new file : dist/linux/bash-deb-builder.sh
- new file : dist/linux/copyright.txt
- new file : dist/linux/package-linux
- new file : dist/linux/popcorn-time.desktop
- modified : Gruntfile.js

Edit 'dist/linux/package-linux' to add you name, email and openPGP public key. Also add the PPA where to upload the files.
All other than the edition to 'package-linux' is automated.

The build by default is 8 packages : amd64 and i386 for *buntu Trusty, Precise, Saucy, Utopic.

The script needs the package 'build-essential' on a debian machine.

As it, you can only build once per release because the orig.tar.xz need to have the same md5sum than the one already in the PPA, in case of error, you need to delete the bad packages from the PPA as the version number is taken from package.json and doesn't accept debian revisions.