Hydrilla

fix handling of --index-json option

add show_default=True to --srcdir option

use parameters to click.Path instead of validating paths manually

make resource dependency specifier an object

change file path format

From now on we'll be using format 'file/sha256/' instead of 'file/sha256-'.

include new schemas in package and in tests

facilitate for including other schemas in submodule and expose them to other packages

move to a namespace package under 'hydrilla'