Merge branch 'hotfix/2.4.3.1'
Merge branch 'release/2.4.5'
Merge branch 'release/2.5.1'
Merge branch 'release/2.5.2'
Merge branch 'release/2.5.3'
fixed: if no config is saved "small" parcel size is shown as default, so it's better to check for a medium package, else return small. Otherwise users
who have upgraded from an earlier version will be shown "small" package size in the admin panel, yet the code will choose "medium". Alternatively it could have checked for an empty config value
fixed: forgot to change the size logic (it's a hot day and had brain glitch). Instead check for empty config value
2014 pricing, international rates updated too
Added Helper test
Moved world zone codes into protected class vars, and replaced switch with if/else
Helper improvements, comments and more descriptive method names
Bug fix: additional weight charges helper didn't calculate correctly
Amended comment
Merge pull request #9 from ashsmith/feature/march2014pricing

2014 pricing, international rates updated too
Bump the version number
Merge branch 'release/2.6.0'
Merge branch 'release/2.6.0' into develop
Add international coverage data (http://www.royalmail.com/sites/default/files/RoyalMail_International_TrackedCoverage_Jan2014.pdf) and helper methods
Add logic to ensure that certain countries are excluded from signed, tracked+signed and tracked
Update tests to still work with the updated allowed countries.

We shouldn't be able to get international signed to France. So update to
Fiji where we can.