Thor should allow namespaces to be turned off

[indirect]

If you are writing a command line utility based on Thor, you don't need Thor to include information about the namespace when it prints usage and errors. For example:

$ bundle foo
The bundler:c_l_i namespace doesn't have a 'foo' task

It seems like it should work like this instead:

$ bundle foo
There is no 'foo' task

It would be very nice to have a way to tell Thor::Task that I don't want namespaces to be mentioned in messages.

[josevalim]

Fixed.