Bring Stabilimentum under test

Signed-off-by: Elana Koren <ekoren@pivotallabs.com>
Refactor Stabilimentum and clean up some bugs

Signed-off-by: Elana Koren <ekoren@pivotallabs.com>
Break CSS link checking out into separate class

Signed-off-by: Elana Koren <ekoren@pivotallabs.com>
Refactor Sieve

Signed-off-by: Elana Koren <ekoren@pivotallabs.com>
Refactor Sieve

Signed-off-by: Elana Koren <ekoren@pivotallabs.com>
Refactor Stabilimentum

Signed-off-by: Elana Koren <ekoren@pivotallabs.com>