Adjusting path_prefix_len for leading slash inconsistencies.

Tasks usually have leading slash in their names, dependencies usually don't but
in some cases(e.g. old rhts rhtsrequires deps) they do.
restraint_fetch_repodeps() now checks if main task and dependency has leading
slash and adjusts path_prefix_len according to that.
Metadata test update

Updating test_metadata.c to include repodeps tests.
Dependency test fix.

Fixing dependency test to work with new restraint_install_dependencies()