Fix test in apply_spec

Signed-off-by: Vipul Savjani <savjaniv@me.com>
Add new class to prepare for apply message

Signed-off-by: Vipul Savjani <savjaniv@me.com>
Allow ApplyPlan to check if new bits have been downloaded

Signed-off-by: Vipul Savjani <savjaniv@me.com>
Persist prepared state and dont download jobs/packages if prepared

Signed-off-by: Jesse Zhang <jz@pivotallabs.com>
correct confusing spec names

Signed-off-by: Jesse Zhang <jz@pivotallabs.com>
back-fill tests for Util.create_symlink