Merge branch 'feature/Package_the_application' into 'develop'

Package the application

**Add package creation script (Issue #43)**

To package the application into a zip file, you will need to go to `/scripts/packaging.php`, and wait for 2 seconds.

The script copy all needed files/directories into `build` directory, then generate the file `dist/framadate-version-date.zip`, then delete directory `build`.

See merge request !48