Connection pool of CouchDB

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
list packages from CouchDB

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
details of package from CouchDB

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>