added method stubs for retrieval of files from urls

Signed-off-by: Peter Menke <pmenke@googlemail.com>
documented LocalFile class description

Signed-off-by: Peter Menke <pmenke@googlemail.com>
documented URL class description

Signed-off-by: Peter Menke <pmenke@googlemail.com>
Merge branch 'feature/140-doc' into develop. Fixes #140
Merge branch 'feature/139-method-stubs' into develop. Fixes #139
Release notes, version bump

Signed-off-by: Peter Menke <pmenke@googlemail.com>
Release 0.0.7, improved docs and method stubs.