base_path added to Recipe struct.

Added base_path to Recipe struct, this will allow to write a working repodeps
tests and takes us one step closer to configurable base_paths.
http_fetch: report error on failed fragment extract

When extracting with 'fragment' report error if nothing was extracted.
repodeps tests in test_dependency

added repodeps tests to test_dependency.c
'Fragment' http tests added.

Added tests to check http fetches with 'fragment' urls.