Merge branch 'release/2.4.3' into develop
Merge branch 'hotfix/2.4.3.1' into develop
Ignore PHPStorm files.
Add Australia as a valid country for Airsure

- According to: http://www.royalmail.com/packet-despatch-low/international-delivery/airsure
Update Airmail prices for April 2013
Update Airsure prices for April 2013
Update International Signed For prices for April 2013
Update First/Second Class prices for April 2013
Update Letter/Large Letter prices for April 2013
Update 9am prices for April 2013 (extrapolated the £1000 and £2500 insurance prices as they are not available on the website)
Update Next Day prices for April 2013 (extrapolated the £1000 and £2500 insurance prices as they are not available)
Amend tests for Special Delivery methods
Update Surfacemail prices for April 2013
Updated shipping method names to reflect Royal Mail updates for 2013
Removed Standard Parcel method, as it no longer appears to exist
Remove 2012 notice from Readme
Remove standard parcel data files
Remove unused method_names.csv
Add promotional message to the configuration area
Don't entirely trust the configuration value for allowed methods, as methods could be removed between releases