Now use ProcessModifier instead of Modifier.toModifyProcess

Using a named object found at import time rather than a delayed function call avoids the possibility of infinite recursion from a cms.Process.load embedded in a process modifying function. In addition, if there are more than one Process described in a configuration, the modify process function will only be applied to a Process if and only if that Process loaded the appropriated module.
Merge pull request #6608 from Dr15Jones/addProcessModifier

Now use ProcessModifier instead of Modifier.toModifyProcess.