avocado.settings: Introduce a config_path param to Settings constructor

So that we can more easily unittest Settings.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
avocado.settings: Eliminate another unneeded method

Another method I thought it'd be useful, but on retrospect,
it's unnecessary for the time being.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
avocado.settings: Introduce docstrings

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
avocado.settings: Add settings_unittest

Add a unittest for the settings implementation. This
module will check the type conversion utility, as well
as functions behave the way we expect them to.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #13 from lmr/settings-unittest

Settings unittest