slapos/recipe/slapconfiguration: Move post-expand-parameter-dict actions to __init__

The reason is: in the next patch we'll want to adjust fetched
parameter_dict with SR defaults, but since currently
_expandParameterDict(), besides expanding itself, also stores result to
options - we cannot do that after - options is not a plain dict - it is
buildout own dictionary-like class

    https://lab.nexedi.com/nexedi/slapos.buildout/blob/d5deb01f/src/zc/buildout/buildout.py#L1377

which on __setitem__ not stores a reference to value, but somehow copies value inside

    https://lab.nexedi.com/nexedi/slapos.buildout/blob/d5deb01f/src/zc/buildout/buildout.py#L1540

so e.g. after the following:

    parameter_dict = {'aaa': 'bbb'}
    options['configuration'] = parameter_dict
    parameter_dict['ccc'] = 'ddd'

parameter_dict is           {'aaa': 'bbb', 'ccc': 'ddd'} and
options['configuration'] is {'aaa': 'bbb' } # no 'ccc' key

~~~~

So let's rework the code so that _expandParameterDict() only expands the
dict and we do (future) postprocessing and options['configuration']
setting in the main driver code.

P.S. isn't it even more logical now?

/cc @vpelletier, @alain.takoudjou

slapos/recipe/slapconfiguration.py

@@ -111,11 +111,18 @@ class Recipe(object):
       parameter_dict = self.fetch_parameter_dict(options,
                                       buildout['buildout']['directory'])
 
-      match = self.OPTCRE_match
-      for key, value in parameter_dict.iteritems():
-          if match(key) is not None:
-              continue
-          options['configuration.' + key] = value
+      # parameter_dict is usually {}, but potentially could be of any type,
+      # e.g. after deserialising { _ -> non-dict json } in Serialised.
+      # If it is non-dict - we just store it as is;
+      # if it is     dict - we process it further.
+      if isinstance(parameter_dict, dict):
+        match = self.OPTCRE_match
+        for key, value in parameter_dict.iteritems():
+            if match(key) is not None:
+                continue
+            options['configuration.' + key] = value
+
+      options['configuration'] = parameter_dict
 
   def fetch_parameter_dict(self, options, instance_root):
       slap = slapos.slap.slap()
@@ -224,18 +231,13 @@ class Recipe(object):
       return self._expandParameterDict(options, parameter_dict)
 
   def _expandParameterDict(self, options, parameter_dict):
-      options['configuration'] = parameter_dict
       return parameter_dict
 
   install = update = lambda self: []
 
 class Serialised(Recipe):
   def _expandParameterDict(self, options, parameter_dict):
-      options['configuration'] = parameter_dict = unwrap(parameter_dict)
-      if isinstance(parameter_dict, dict):
-          return parameter_dict
-      else:
-          return {}
+      return unwrap(parameter_dict)
 
 class JsonDump(Recipe):
   def __init__(self, buildout, name, options):