Added variables to edit page

[kanedaki]

I've been in need of passing variables around to yaml strings but the user that edited the strings was not able to see them. This PR fixes that.

I've added a new serialized hash to the model so it holds the variables (options) that are passed to the translator, so we can get them in the edit page.

Also, the variables are shown in the edit page.

I will provide tests tomorrow :)