The postbuildscript module's 'onsuccess' and 'onfailure' parameters
names were slightly confusing. This change deprecates those parameter
names and replaces them with less confusing names. The new names
are more closely matched to the ones that get added to the xml.
Change-Id: Ifb76129852816aa3f8ee6bb7f609a2344ccc7a69
Avoid imposing hardcoded order of the scripts within the module and
instead favour the order of the input data. Combined with use of ordered
dicts for yaml, this ensures that users may control the order of the
various steps to use with the post build scripts from yaml.
Change-Id: Icf540a53cb6f1b13f80f09d9103610aee10d3861