Added credit to TfL for each page

Added a footer to each page to give credit to TfL for
providing the data. Thus other GUI improvements
Refactored around ServiceStatusLogic to use MVC

ServiceStatusLogic now uses ThisWeekendLineModel to share data
with GUI, GUI in exchange is changed to use SilicaListView.
Added ViewPlaceholder

Added missing ViewPlaceholder to ServiceStatusPage
Added different filters to DisruptionProxyModel

Added new filters to DisruptionProxyModel to be able to request inactive
disruptions. GUI also had to be adjusted to accomodate for it. A few
other minor GUI improvement has also been made.
Optimized tubemap.png image

Size of tubemap.png has been reduced considerably.
Fixed Bug where loaction returned an emtpy string

Fixed a bug where parser would find empty string instead of the
location. It is a temporary fix, until a better solution is found, now
downloading and parsing doesn't happen concurrently.
Bumped Version number

Bumped version number to 0.3.1 and amended Changelog to match it.
Added a proxy model

Added a proxy model so that both Service Status' model
and This Weekend's model can be sorted alphabetically, otherwise they
would differ from one another.
Fixed bug

Fixed bug when internet connection is not available,
GUI doesn't show that it's parsing but rather asks user to refresh.
Changed LondonSailUtilities module name

Changed LondonSailUtilities to harbour.london.sail.utilities in
order to comply with Harbour rules.