The previous implementation used int64 for both, which can be mixed up
easily. Using distinct types adds a layer of type safety checked by the
compiler.
* added functionality to scan docker images with digests instead of tags
* cleaned import statement
* added unit test for baseAndTag parsing + remote digest scan
* Implement CommonSourceUnitUnmarshaller
* Add SourceUnitUnmarshaller to all sources using
All sources, with the exception of git, will use the CommonSourceUnit as
they only contain a single type of unit to scan.
* Fix method comments to adhere to Go's style guide
Miccah