Fixed the updating of forecast months when the current month is changed

This pull request fixes two problems that were found to effect the updating and display of forecast months in the seasonal forecast part of the app.

Firstly, when the current month was changed the 6 forecast months displayed were incorrect. This was simply due to the current numerical month value from the drop down being handled as a String rather than parsed to an Int.

Secondly, the 6 months displayed across the x-axis of the seasonal graph did not update when a new month was selected. This was due to the required attribute not being available to the view to listen to - this was fixed by re-wiring the models a bit.

Please review and merge. Thanks