Make key storage system pluggable

[trevjonez]

Currently we just dump the keys and extra files into the project dir. Those PNG files and json files can take up a considerable amount of storage after time. One would think some people might want to be able to use an external database or something crazy to store their key files.

Should be able to make an interface that provides some sort of I/O streams and run comparisons from those. DSL configuration, etc...