Use latest translations during 'quickly run'

Maybe you do something like:
$quickly run
just runs the default language, but
$quickly run nl
would run the dutch translation, for example

Trying to summarize from the question cited in the first post:

There is currently no way to see the project with its translated strings using `quickly run`, the normal way to run the application during development. To test the translations, one would need to create a package, install it and run the installed application. This is not an optimal way of testing the translations.

It seems to me that the way most of the programming languages/development frameworks/etc. work is that they use the latest available translations [if available] when running the application directly from source control. In the sense "if there is a .mo file for the current locale use it, else use the default [English] string".

This doesn't mean that the .mo files are compiled each time the application is run, rather the .mo files need to be compiled explicitly.

What I have in mind is the following:

- Retrieve the latest translations (.po files) from Launchpad
- Compile the .mo files (currently with `python setup.py build` since there is no specific Quickly command for that [bug #683342])
- Run the application with `quickly run`. At that point the application is displayed in the user's locale (if there are translations available for this locale)

We might even expand this behavior by adding a parameter to `quickly run` to be able to manually set the locale, as suggested by Rick Spencer, but I would propose to separate this from the current issue. If we are already able to see the application in the current locale using `quickly run`, then we could open a new bug report for supporting manual selection of the locale (second tier priority in my eyes)