Create the Firefox addon from gulp

[cmolina]

I like to use the makefunction (mk-tmp-dir.js) from a gulp task.

The problem is that its options parameter has a cwd attribute which is used only for loading the package.json, but the rest of the chrome code is loaded using process.cwd() (even when they are in the same directory).

The expected behaviour is to load all the chrome files from options.cwd, so you do not have to change directory from gulp to successfully build the addon.