v0.2.4

With 0.2.4 many of the outlying project goals and initial edge cases have been addressed.
Here are some highlights:

• Package size reduced by moving pocket managing methods into their own file as optional imports including:
• tidyPocket(), emptyPocket(), getAllPocketKeys().
• numbers can now be added to cargo.data without first being stringified.
• You can now use .set() to set cargo.data and cargo.expiry values without one or the other being overwritten as null
• All methods and functions that operate directly on a store now return null consistently if key associated with the current instance isn't found in the store.
• Increased test coverage
• Flushed out documentation