What to run?

[eregon]

Currently mspec is run without any argument, which means it defaults to :files, which is:

get(:language) + get(:core) + get(:library)

Should we run :optional (the same as :capi)?
Should we run command_line?
Both pass on rubies 2.0 - trunk.
I think we should run them by default since they do not take long and improve coverage.

[eregon]

Fixed by e5d0bd0 and 261855a.
All specs are now ran on Travis.
(Readline specs are still currently excluded for all runs, I plan to enable them if they prove stable enough)